The online surplus website Old Grouch’s Surplus sent out an email with a neat list of ideas if you are like me and have more of these than you know what to currently do with.
Today we have a guest post from sporadic contributor and quasi-Looserounds member “CJ”, about his favorite topic.
The following is repost from Hognose at weaponsman.com. Weaponsman is an excellent weapon related website that is a friend to this website and also a favorite internet stop.
The most annoying person in the world is the write-only device. You know that guy: he never shuts up, yammering on and on, and never stopping to listen, only to take a breath. As you might expect, that habit which makes everyone want to kill him in a peacetime classroom or office, makes it easy for the enemy to literally kill him in combat.
There is much to be said about stealth and silence. The first thing that we will say is this: truly silent motion across terrain is not possible. It is an ideal for which you must strive, but even Mark Twain recognized it as nothing but a literary convention, when he was beating the defenseless James Fenimore Cooper senseless in a battle of wits:
Another stage-property that he pulled out of his box pretty frequently was the broken twig. He prized his broken twig above all the rest of his effects, and worked it the hardest. It is a restful chapter in any book of his when somebody doesn’t step on a dry twig and alarm all the reds and whites for two hundred yards around. Every time a Cooper person is in peril, and absolute silence is worth four dollars a minute, he is sure to step on a dry twig. There may be a hundred other handier things to step on, but that wouldn’t satisfy Cooper. Cooper requires him to turn out and find a dry twig; and if he can’t do it, go and borrow one. In fact, the Leatherstocking Series ought to have been called the Broken Twig Series.
It was always a Cooper white man who broke the twig, because Indians were born to patient stealth, at least in his universe. (Cooper, one must remember, was no frontiersman, but a cashiered Naval Academy midshipman). The Indian, in fact, was no more capable of silent movement than a ninja, an SF soldier, or you.
It was a crushing disappointment to learn that we would not, in SFQC, learn the Indian ninja art of silent walking on dry oak leaves. Instead, however, we learned something more practically useful: how to be quieter than the other guy, and as quiet as we needed to be.
If silent movement is not possible — and it isn’t, if your enemy can’t hear you, his dogs, with their superhuman hearing, can — then moving stealthily at night requires several things:
- Masking local noise with background noise;
- Altering the kinds of noise to attenuate sound travel; and,
- Periodic listening halts.
The first two are fairly obvious: you can move much more rapidly without giving yourself away when a train is passing by, and high-pitched sounds travel poorly. (You do need to bear in mind that sound travels differently in different atmospheric conditions). The most complicated of those three principles of night movement to apply is the periodic listening halt.
Immediately after inserting, assembly, or crossing a danger area (of which more in some subsequent article), the patrol or team must conduct an initial listening security halt. While the details of the halt may vary, something like this works:
- Freeze in place.
- Remain there for five full minutes.
- Maintain 360º security.
- Actively listen the whole time.
- After five minutes, make a decision: move, or continue listening?
Why five minutes? You can change that time if you like, but it’s a good minimum because it’s quite a long time to be frozen in one place. Even a patient enemy, who stops when you do, will move and give his existence and position away before five minutes is up.
Active listening? That means concentrating on listening. You’re not only listening for the enemy, but also to develop a mental picture of what normal night sounds in your location are like. What are they like immediately when you stop? If you have been halted for a time, are there animal noises that come back (and that presumably stopped while you were moving)? Knowing this gives you an edge in the woods, compared to someone who doesn’t.
After the initial halt, the element leader must have a way to silently signal the element to begin moving again. If there is sufficient illumination, hand and arm signals may be effective; if not, touch signals should be used. Only in the most extreme case should a command be verbalized, and then, it should be whispered (remember, a higher-pitched whisper will travel much more poorly than a normal-pitched vocalized word — which is a good thing in a night full of hostiles).
It goes without saying that all these modes of command and control, and the listening security halts themselves, must be practiced in controlled conditions in garrison before attempting them in the face of an armed enemy. Night combat patrol operations are at the far end of a long crawl-walk-run pipeline; they’re the Boston Marathon of crawl-walk-run.
Animal and bird sounds make both effective stealth command and control means, and also excellent “cover” if you inadvertently make a sound in the possible presence of the enemy. Do a Leatherstocking and break a twig, or snap back a branch? The risk of exposure may be mitigated, if you can fake the snort of a deer or porcine species native to the area.
Once the element is on the move, further listening security halts should be executed at relatively short but variable periods. You can set these by distance or by time; it’s also helpful to be cognizant of terrain. If you have just passed through some stuff that was impossible to be truly quiet in, like dense mountain laurel or the dry leaves of an oak forest in winter, a listening security halt on the far side should be able to reassure you about the prospect of being tracked or tailed. As in all patrol technique, principles are iron but the means of serving those principles are best mixed up so as not to simplify the enemy’s counterpatrol planning.
Don’t be the foot-shufflin’, twig-snappin’, noise-makin’ equivalent of the yammering guy in the first paragraph. On patrol, the silent man comes home; the guy who loves the sound of his own noise dies from it.
For a long time “ceramic” meant “expensive” when it comes to body armor. Either pay at least $500 at a minimum for a ceramic level IV plate or settle for a less expensive and less effective steel plate. As more regular folks buy armor for just in case, market pressure has forced manufacturers to adapt. Some manufacturers are producing tougher, “level III+” steel plates that can stop some of the high velocity .223/5.56mm threats that regular level III steel plates cannot. At the same time, ceramic plates have also become more affordable. Highcom Security actually offers a level IV ceramic plate at a price lower than some steel plates. It is available in a variety of sizes, curve options, and cuts, but in the 10″ x 12″ shooter’s cut, single curve style that is so popular, the price is $159.
At that price, one might reasonably suspect how effective the plate is. As the sci-fi writer Robert A. Heinlein was fond of saying “There ain’t no such thing as a free lunch.” It is quite reasonable to be suspicious of the quality at such an attractive price, but the plate has far exceeded any reasonable expectations.
Everything done in the test above shatters expectations, if you’ll pardon the pun. The hammer impact far exceeds anything you could reasonably expect to encounter in field use and the .358 Win is also something the plate was not designed to stop. Bear in mind that when this test was conducted, the plate had already stopped a 405 gr .450 Marlin at almost 2,000 fps. The plate then went on to stop a round of 7.62x51mm M61 AP.
Again, it is important to bear in mind that the plate had already sustained some ridiculous abuse before stopping the armor piercing round.
As tough as the plate is, it is also a little heavier than other plates with the same NIJ rating, but at 7.2 lbs for the 10″ x 12″ shooter’s cut, the difference is not huge and still lighter than steel plates of similar dimensions, while providing a great deal more protection than steel plates.
As always, the burden is upon you to do comprehensive research and determine your own priorities before purchasing any personal protective equipment. It is likewise important to stress that training matters a great deal more than equipment. No amount of gear, no matter how cool can make up for poor training. The more you sweat in training, the less you will bleed in a fight.
Some things really are better. Cold beer is better than warm beer. Empire Strikes Back is better than Return of the Jedi. But in most cases, one thing is not really better than another thing, just different. As much as it pains me to admit, PCs are not better than Macs, just different. Depending on your priorities, one or the other may be a better fit. This concept applies to body armor as well. There is a perception that level IIIA soft armor is “better” than level IIA because it is rated for higher energy threats. Level IIIA armor also tends to be heavier, stiffer, hotter, and generally less comfortable than level IIA. Anyone who has worn armor for a living knows that comfort isn’t nearly as superficial as it might sound to someone who has not worn armor for long periods of time. There are a number of other factors that should be considered when selecting armor such as weight, thickness, threat rating, and of course, price. There are some other factors that may be overlooked, though.
One factor is the fact that different types of body armor might perform differently with specific threats, even if they have the same threat rating. By way of example, this level III steel plate was able to stop a round of M61 7.62x51mm AP.
When shot with the same ammunition from the same barrel length, a ceramic level III plate was perforated, though.
How can this be? Every internet operator worth his keyboard will tell you straight up that ceramic armor is “better” than steel, so how is it that the steel can stop a round that gets through the ceramic? The fact is that the real world is not a video game. Ceramic armor is not a +10 damage resistance over steel armor. Different armor types perform differently across a spectrum of velocities, bullet weights, and types of projectile construction. The materials used in each plate work differently to stop bullets. That does not mean that the steel plate is superior, either, though. The same plates had opposite performance when tested against the Army’s new M855A1 62 gr EPR.
In this case, the ceramic plate stopped the round but the steel plate was perforated.
Both plates carry the NIJ level III rating. Shouldn’t that mean that they will stop the same ammunition? In a way, that is precisely what that means, but we have to put a very fine point on that statement. It means that they will both protect the wearer from 7.62x51mm M80 at 2,780 fps by preventing the round from reaching the wearer but without deforming more that 1.7″. This last bit is often overlooked as well. Soft body armor and composite rifle plates deform when struck by a projectile. Often, that deformation is substantial, as seen in the video below:
The NIJ specifies that the degree of back face deformation should be measured by measuring the depression left in a clay block placed behind the test article. In this informal test, the clay used is not exactly the same type and consistency of the clay specified by the NIJ, but it gives a general picture of the difference between the back face signature produced by these two plates when struck with the same projectile.
Although they are the same threat level and were struck with exactly the same ammunition, the degree of back face deformation on the ceramic composite plate was profound, while the steel plate showed virtually zero deformation.
Please understand that this series of tests should not be taken to indicate that steel is “better,” either, just that steel and ceramic work differently. The two plates shown here vary substantially in price, thickness, and weight as well as the factors discussed in this article. They perform differently, but one is not necessarily “better” than the other. Both plates will still protect the wearer against the vast majority of small arms munitions, though.
As always, it is your responsibility to do extensive research before purchasing any personal protective equipment. Also remember that training is far more important than equipment. There is no amount of gear that can make up for a training deficiency.
I spent some time thinking as to how to go about writing this article and have changed things from how I initially wanted to approach it.
At first I was going to talk about all the different meanings of night vision terms and what they do, but there is already lots of good information online about this already. What is lacking is a strait up answer to is it worth it to buy high end quality night optics.
If you are reading the articles here it is obvious you are interested in firearms and shooting. At some point you have looked at night vision and probably thought “man that’s expensive stuff, maybe one day” and written it off as something to do at a later date or if you won the lottery.
While it can be a daunting task figuring out exactly what you need, what works with what, and coming to terms with spending the money on it we can simplify things quite a bit and make it a lot easier. On to the question at hand, is it worth it to buy high end (gen 3) night optics?
Without a doubt the answer to this is yes, plain and simple. Once you have the opportunity to look through a high end device you will be astounded and think no wonder our military loves to work at night. There will always be people saying “I have a gen 1 optic and I can see fine with it there’s no need to buy the expensive higher end optics”. My answer to this is these people probably have never looked through a gen 3 device.
Back in April of 2014 I decided it was time for me to take the plunge in to night vision, but like everyone else I was not sure where to start but I knew it was going to be with a pvs14. I saw lots of places selling them online but found mixed results of the end product, some being very high performing devices then a week later someone got one that was less than stellar from the same vendor.
I knew Tactical Night Vision Company (www.tnvc.com) had a good reputation online for being of quality so I shot off an email and a couple phone calls to test the waters, I never mentioned Loose Rounds in any correspondence. I spoke with a few different people as well as the CEO Vic who I have chatted with a few times and personally took care to make sure I was squared away with my purchase.
All items I purchased were out of my own pocket with no discount. I opted to go with what is considered an entry level setup. A Team Wendy LTP bump helmet, USGI Rhino mount, and a TNV/PVS-14 with an ITT tube.
When I received everything in I was especially surprised when looking at the data sheet for the tube, with specs that exceeded Omni 8 military specs.
I then started setting it up for me, I’m using a surefire M1 for additional illumination when needed, a TLR1 pistol light for a white light option, an IR beacon on top, and a counterweight on the back to help balance things out.
I also bought a small IR laser to aid in aiming at night, which will be getting replaced by the Atpial-C which will be reviewed soon. I had no trouble wearing out a 6 inch steel plate at 100 yards under starlight only. I feel comfortable at being able to ID a man size target out to 200-300 yards and is possible to get hits on target at 150 yards once you get accustom to working with the laser and a solid rest.
For the past 10 months any chance I get I take off in to the night to see what working at night is all about. Sometimes tracking down coyotes, other times shooting from barricades and normal drills I would do during the day. It definitely changes your outlook on things, no longer are you limited to only working in the day time or giving away your position by using a light at night.
In the future I will be looking at ways to get some quality “down the tube” images from the PVS-14 to illustrate what exactly I am looking at as the pictures I have tried taking don’t properly reflect the devices capability as well as how I approach aiming with the laser, and working with different types of cover from foliage to solid objects.
To wrap things up if you have ever been interested in night vision or are using a lower end device, yes it is worth it to pony up for the higher end optics. While there is no definitive go buy this solution to what you should buy, giving TNVC a call and telling them what you intend to do is a great place to start and rest assured there will be no questions regarding quality of the device you receive or customer service like other vendors you may deal with.
Part 2 of the debunking of the absurd myth that the M4 has caused the death of US military people due to failures. Once again this is the sole work of the writer from www.weaponsman.com, THE technical website on all things military weapons related, among other topics. We again highly recommend all follow them. Part 1 is actually below this post due to the way our website is set up. Both are long posts but very detailed and worth reading if you are a real student of military fighting weapons.
In the enormous1 part one of the series, we reacted to a brain-dead article published in The Atlantic by a retired Major General, who has, since his retirement 20+ years ago, been a lobbyist for defense firms and TV talking head. (Before he got his stars he was an artillery officer). We may have more to say about our brain-dead GO in a subsequent post, but we think we raised some good points about his article. We weren’t the only ones. He also ticked off Nathaniel Fitch at The Firearm Blog, and we heard, also the guys at Loose Rounds (you know, the ones that fire M4s at 1000 yards and make the steel ring? Those guys?), and no doubt there are other places in the gunosphere flaying him. The point of today’s increment is not to make the rubble of the General’s small-arms expertise do a dead-cat-under-155-battery-closed-sheaf-fire-for-effect bounce, but to discuss the technical limits of a shoulder weapon in sustained automatic fire.
Because today is a travel day, this article was mostly-dictated for speed. Therefore, we fear we have some typos we haven’t found. Let us know in the comments.
Sustained Auto Fire and Heat
Many of the problems the M16A1 had in Vietnam, and even in adoption and acceptance prior to Vietnam, were caused by the heat of sustained autofire. It was particularly problematical after powder changes made a dramatic impact on the cyclic rate of the rifle. Indeed, Colt got a contract mod allowing weapons that had a much higher sustained rate than originally specified to be accepted.
Thermal waste is a huge problem for gun designers, and it’s been jamming automatic weapons since Maxim’s day. The heat is generated by the combustion of chemical powder in the chamber in barrel, but also by the metal-on-metal contact between bullet and barrel, which swages the impression of the rifling into the bullet and imparts a spin of hundreds-of-thousands of revolutions per minute to the bullet. The friction between bore and bullet is a significant contributor to barrel heating.
If you were in the service, you were made to memorize something about your rifle being a “shoulder-fired, magazine-fed, air-cooled, selective-fire…” weapon. The “air-cooled” seems like a historical artifact now; the last liquid-cooled small arms were the 1917 Browning machine guns, which were last used in World War II. All modern small arms of all nations are air-cooled. That means that the air around the barrel must carry the heat of the barrel away. Meanwhile, for each round, the barrel gets hotter, because firing’s ability to load up the temperature is greater than the cooling system’s ability to remove heat. (The original M16A1 had a patented passive design for convection-driven airflow, removing the heat from the holes at the top of the handguard and drawing new air in at the bottom. Designs since then have made efforts to maintain that cooling, with little success).
Because this post is long, and involved, we’re going to split it. Ahead, we describe the bad things that happen when barrels get hot; the results of M4 cyclic rate tests (including instrumented and well-documented tests to destruction), and Click “more” for the next three thousand or so words, a few pictures, and pointers to where you can find some of the math.
Bad Things Happen When Barrels Get Hot
The peak temperature area in the barrel is usually about three to seven inches forward of the chamber, depending on caliber (according to the references, on 5.56 mm rifles, it’s about four inches). This is where the thermal stress is at peak, and it also has to support all the rest of the barrel (and anything that may be attached to it, from a Surefire to an M9 bayonet), so when the gun is going to fail, it’s probably going to fail near here.
As more rounds are fired, more heat builds up, because it is being added at a higher rate than it can be radiated away. As the temperature rises, bad things happen:
- You have a risk of propellant cook-off. Weapons that fire from closed-bolt are especially prone to cook-off. At a critical temperature, the powder or primer will self-initiate. As the temperature rises, the amount of time a round has to sit in the chamber to heat-soak to the point that it self-initiates declines. At first it takes minutes, then seconds, then rounds can actually cook off before the automatic firing train fires them, and finally, they can cook off out of battery. Usually other damage disables the weapon by this point. This article at DTIC shows some of the tools the .mil has to model heat transfer, and compares predicted cook-off data to observed, unfortunately in a large-caliber small arm (30mm Mk44 vehicular cannon). They generated this equation (after Visnov) that shows :
Time to cook off (minutes) = 10.129 x 1025 x (cook-off Temp – degrees C) x 10-10.95
The cook-off temp is a constant for a given powder, and can be experimentally determined by heating the powder on a steel plate.
In the test, they did not maintain continuous fire but bursts of fire according to a firing table, then followed by letting a round sit in the chamber. Their cook-off times in live testing ranged from about 10 to about 30 minutes testing. Note that brass provides better protection from cook-off than aluminum cases, which in turn provide better protection than steel.
In another experiment, Hameed et. al. built a “Chamber simulator” and developed working chamber temperature-time curves for producing cook-offs in a 7.62mm brass case with Bullseye powder. They found that below 170ºC chamber temperature, cook-offs were unlikely, and that by about 240º, the cook-off time was down to seconds.
- It can cause failures to extract. This actually led to a change in the formula for Black Hills MK262 Mod1 ammo, as reported by Shooting Times:
[A]n improvement to temperature sensitivity came along in 2005. [Black Hills President Jeff] Hoffman said the last change came after Black Hills technicians noticed some failures to extract (FTX) in their test M4 and short-barreled rifles, and that it was the most difficult problem to solve.
“We initially thought the FTXs were possibly related to higher port pressures,” Hoffman said. “The M4’s port pressure is around 25,000 psi, much higher than the SPR due to the location of the gas port on the respective guns. We looked at brass, powder, everything.”
It finally came down to chamber temperature. The test specification called for the ammo to be baked at 125 degrees for two hours and not exceed pressure limits when then chambered and fired. When Black Hills engineers started firing test guns far beyond the specified rate of fire, the chamber temperatures got much hotter than 125 degrees. In an extended firefight, soldiers could heat up their rifles with a few mags, and then during a lull in fighting, a chambered round would sit in a 200- or even 300-degree environment. That significantly increased chamber pressures and induced failures to extract.
“After we figured it out, I was surprised that it hadn’t come up before,” Hoffman said. “We’ve gone from bolt rifles to eight-round Garand clips to closed-bolt, select-fire rifles. SF guys never had an issue because they are trained to fire two or three rounds per target and very rarely go full auto.”
It only took Black Hills 75,000 rounds to sort out the problem—a chunk of the 250,000 rounds Hoffman figures the company fired developing and lot-testing the load. Finally, the round was issued. Interestingly, the ammo always did meet specs, even the ammo that Black Hills engineers felt needed improvement—they just found a way to make it better. The Navy began changing test specifications based on what Black Hills learned—and shared—during development and testing. The improved round was a hit, no pun intended, with operators in-theatre, and usage went through the roof. Not only did the ammo perform well for its intended purpose—long-range shooting—but did equally well in short-barreled rifles like the M4 (14.5-inch barrel) and MK 18 (10.3-inch barrel), which leads to a discussion of lethality.
- It can cause the barrel itself to fail next time it is used. At a very high temperature, the barrel is heated until it loses its temper, which can cause an invisible (and undetectable by gaging) failure of accuracy. This was first noted with aerial machine guns in WWII, as we noted here before.
- If continued, it can cause the barrel to fail catastrophically whilst firing. Stripped of its heat treatment and heated to the metal’s plastic temperature, the barrel droops. At first, rounds extending through it will sort of “hold it up” but soon it will be unable to contain the pressure and will burst.
- If the barrel doesn’t fail first, heat can cause the gas tube to fail. Weakened by high temps, the tube lets go.
Any gun can cook off. The USN famously cooked off a 5″ on the destroyer USS Turner Joy in 1965 during a Vietnam War shore bombardment, killing three sailors and wounding three more.
Results of M4 Cyclic Rate Tests
Colt has, in fact, tested M4s at cyclic rate to destruction and has made these tests public. C.J. Chivers, a former Marine, has reported on these tests in a long and readable report for, of all things, the New York Times. That report was Part II of a previous report on M4 manufacturing there. We were unable to extract the Colt videos from the Times page, but it’s very much worth reading, anyway.
After the Colt tests, the Center for Naval Analyses did a report. We don’t have the report, but Kirk Ross at the US Naval Institute’s Proceedings Magazine did an excellent and thoroughly-documented synthesis of the then-known information, including the CNA report and the Colt tests, a DOD survey of weapons users, and SOPMOD program office documents. Ross’s article is an excellent short piece on these issues and we strongly recommend it.
A lot of what we know about the M4 under duress comes from mid-1990s research. In the 1990s, as the then-new M4A1 carbine began reaching special operations units that shot them a lot, they began blowing them up. In June, 1995, 10th SF Group had two cook-offs. In September, the 1st Battalion of the 1st SFG reported multiple problems, including cook-offs. In May, 1996, 7th Group blew one up in its then-home-station of Fort Bragg. In August, 1996, 3rd Group blew one up on an African JCET; one USSF was injured by gun shrapnel. 5th Group and the 1st Ranger Bat also blew up guns around this time, and that began to worry SOF soldiers and leaders — and the armament procurement guys. The Army resolved to test M4s to destruction to determine what was going on. The one thing they knew was that the destroyed guns had been fired a lot, primarily full-auto fire at cyclic rates, often “burning up” excess ammunition at the end of an exercise (wasteful, but the Army makes it very difficult to turn back in unused ammo, and the Air Force is snippy about transporting it).
In 1996, ARDEC’s Jeff Windham conducted tests-to-destruction to determine whether, as then rumored, M4 barrels were more prone to failure than the M16A2 barrel. These were early M4A1s with the M4 profile barrel (like the one we carried in Afghanistan), and the M16A2 controls in the test were modified to fire full-auto by subbing in M16A1 fire control parts. The guns were fixtured and fired full-auto. The intent was to fire one of each fully-instrumented weapon to failure. Initially, an M16A2 was destroyed:
The M16A2 was fired continuously using 30 rounds bursts. Shown in Table I are the rounds to failure, time to failure and maximum barrel temperature of the barrel. Muzzle flash increased and there was a distinct change in the sound of the weapons firing approximately 30 rounds before the barrel ruptured. There was also noticeable drooping (about 1 inch at the muzzle) of the barrel just prior to the barrel rupture. The barrel ruptured at 491 rounds with an approximately ½ inch hole in the top of the barrel about 8 inches in front of the chamber. The barrel was bent approximately 5 degrees and bulged in several locations along its length (see figures 4, 5, and 6). A plot of barrel temperature versus time at each thermocouple location is shown in figure 7.
Given the hypothesis that the M4 would die before the A2, Jeff fixtured the sacrificial M4A1 and set up 18 magazines, containing 540 rounds, and then fired them. But while the barrel was ruined, it didn’t actually burst:
The M4A1 Carbine was fired for 540 rounds. It was thought the M4A1 barrel would rupture well before this point, therefore only 540 rounds were loaded for firing. This weapon’s barrel was noticeably bent and bulged at the end of the test (see figure 8). A plot of barrel temperature versus time at each thermocouple location is shown in figure 9.
Oops. Back to the testing bench, with another M4A1 selected as a sacrifice to the gods of knowledge.
A second M4A1 Carbine was fixtured for testing and fired until barrel rupture. Muzzle flash increased and there was a distinct change in the sound of the weapons firing approximately 30 rounds before the barrel ruptured. There was also noticeable drooping (about 3/4 inch at the muzzle) of the barrel just prior to the barrel rupture. The barrel was ruptured at the 12 o’clock position approximately 4 inches in front of the chamber. The rupture was approximately 1V4 inches long and 5/8 inches wide. The barrel around the rupture was bulged out about 30 percent larger than its normal diameter. The barrel was bent at the hole approximately 3 degrees (see figures 10 and 11). A plot of barrel temperature versus time at each thermocouple location is shown in figure 12. There was an approximately 30-second delay in firing of this sequence which can be seen in the temperature plots. This delay allowed additional cooling of the weapon and may have increased the number of rounds to rupture by 30 to 60 rounds.
Here is the Table 1 from the report. The other figures and tables referenced in the quotes are in the report, which is linked in the Sources below, although the photo reproduction is of very low quality.
SOCOM sent a safety message as far back as 1996, presumably based on Windham’s research (although we didn’t notice if they said that) about cook-offs with sustained fire. It is reproduced in this archived ARFCOM thread. We recall receiving this message with a red-bordered safety cover sheet. The thread poster has good advice. Here are a couple of lines from that message:
Sustained firing of the M16 series rifles or M4 series carbines will rapidly raise the temperature of the barrel to a critical point.
Firing 140 rounds, rapidly and continuously, will raise the temperature of the barrel to the cook-off point. At this temperature, any live round remaining in the chamber for any reason may cook-off (detonate) in as short a period as 10 seconds.
Sustained rate of fire for the M16 series rifles and M4 series carbines is 12-15 rounds per minute. This is the actual rate of fire that a weapon can continue to be fired for an indefinite length of time without serious overheating.
The sustained rate of fire should never be exceeded except under circumstances of extreme urgency. (Note: a hot weapon takes approximately 30 minutes to cool to ambient temperature conditions).
Cook-offs out of battery result from a round which cooks off when the bolt is not locked or a round which cooks off as the user is trying to clear the weapon.
Burst barrels result when the weapons are fired under very extreme firing schedules and the barrel temperature exceeds 1360 degrees Fahrenheit. When the barrel reaches these extreme temperatures, the barrel steel weakens to the point that the high pressure gases burst through the side of the barrel approximately 4 inches in front of the chamber. This condition can result in serious injury.
That is, of course, exactly the failure mode in the first M4 video at Chivers’s report. And this is from a message from 1996, so SOCOM’s weapons experts knew it almost 20 years ago, and more than 10 years before Wanat.
600-700 degrees F is where cook-offs begin, and that’s reached in as few as 140 rounds on rapid semi-auto fire.
Here’s a table with some key temperatures for you:
|Temp F||Temp C||Rounds||Comment|
|230||110||30||semi-auto M855 in M4|
|278||137||30||full-auto M855 in M4|
|600||316||140||semi-auto; threshold of cook-off|
|700||371||?||frequent cookoffs, barrel weakened|
|1360||737||~500||semi or full, catastrophic failure|
|© Weaponsman,com 2015|
How to Deal With Heat Limits
The Training Answer: First, every GI should see those Colt test videos and know what his gun can, and can’t, do. While the Black Hills guys were correct in noting that SF/SOF guys usually manually fire single shots or short bursts, even most of them don’t know what happens when a gun goes cyclic for minutes at a time. A good video explaining “why you can’t do that” would be a strong addition to training, not only for combat forces, but for support elements who may find themselves in combat and feel the urge to dump mags at cyclic rate.
The Morale Answer: Every GI should see the same done to AKs as well. There is a myth perpetuated by pig-ignorant people (like General Scales) that the AK series possesses magical properties and that the American weapons are crap. In fact, nobody I know of at the sharp end is at all eager to change, perhaps because the laws of physics and the properties of materials apply just as firmly to a gun originally created by a Communist in Izhevsk as they do to a concept crafted by capitalists in California. If you’ve ever fired an AK to destruction, you know that it grows too hot to hold, then the wooden furniture goes on fire, then, if you persist on firing it full-auto, it also goes kablooey. Not because there’s anything wrong with this rifle, but the laws and equations work the same for engineers worldwide.
The Systems Answer: As you can see from the Colt videos, if you clicked on over to Chivers’s article, thickening the barrel nearly doubled the rounds to catastrophic failure on cyclic. An open/closed bolt cycle might have practical benefits. They wouldn’t show up in sustained heavy firing like the destruction tests, but they might show up in how a weapon recoups from high temps, and open-bolt autofire would eliminate cook-offs, at least. But any such approach needs thorough testing.
The Wrong Answer: Replacing the M4 with something like the SCAR or the HK416, something that is, at best, barely better, that is much more maintenance intensive, and that, contra Scales’s assertion that his undisclosed client’s weapon is “the same price,” is twice (SCAR) or three times (416) the money. (The 416 mags are the best part of the system, though).
It would be interesting to duplicate Jeff Windham’s M4A1 destruction tests with AKs and with other competitors, like the 416. Scales says a piston system like those (never mind that each one is a very different design) would not fail under the conditions seen at Wanat. We’ve seen from the information here, that the failure of firearms under high rates of fire is driven by the physical problems of waste heat and metallurgy. Our prediction is the laws of physics apply in Russia and Germany as well.
Did Weapons Cause Deaths at Wanat?
We’ve talked about how the weapons fail, when they fail, today. But in the previous post, we were looking at this in the context of a very important question: did weapons deficiencies cause deaths at Wanat? We reached our conclusions. In The Atlantic, Major General Scales, the undocumented lobbyist and long-retired talking head, reached the opposite conclusion, and asserted that the nine fatalities that day resulted from, specifically, M4 failures. We are not sure whether his problem is lack of familiarity with the material we’ve presented here, or whether it’s an integrity issue, but we think we’ve rather conclusively made the point that any honest answer comes back, “No.”
But it’s worth noting what the other investigations decided.
- The historical investigation, both the Cubbison and the final, come up, “no.”
- The RAND report does not fault the weapons. It does suggest some theoretical future weapons developments, such as miniguns or thermobaric weapons, and points out the dead-space problem without making a specific suggestion of how to address it.
- The Army 15-6 investigation, came up “no,” and said so explicitly.
- The DOD Inspector General investigation, that was extremely critical of the leadership of the company, battalion and brigade, did not mention weapons as a factor.
And so we’re not really in bad company, even though were on the other side of a Major General on this.
1. A good web article is about 300 words. A good newspaper column is about 700 words. Because we have faith in our readers’ ability to follow pieces of greater length and complexity, we frequently go to 1000 or even 2000 words (although our mean comes in around 600). That article was 3,129 words. And well illustrated, too.
Chivers, CJ. The Making of the Military’s Standard Arms, Part II. New York Times (online): 12 Jan 2010. Retrieved from: http://atwar.blogs.nytimes.com/2010/01/12/m4-and-m4a1-guns/?_r=1
Department of Defense. MIL-STD-3029: Department of Defense Test Method Standard: Hot Gun Cook-Off Hazards Assessment, Test and Analysis. Washington, DC: DOD, 23 July 2009. Retrieved from: http://everyspec.com/MIL-STD/MIL-STD-3000-9999/download.php?spec=MIL-STD-3029.022917.PDF
Guthrie, J. Reviewing Black Hills’ MK 262 Mod 1 Ammo. Shooting Times: 21 Mar 2012. Retrieved from: http://www.shootingtimes.com/ammo/special-forces-to-civilians-black-hills-mk-262-mod-1-review/
Hameed, Amer, Azavedo, Mathew, and Pitcher, Philip. Experimental investigation of a cook-off temperature in a hot barrel. Defence Technology.Volume 10, Issue 2, June 2014 (28th International Symposium on Ballistics), Pages 86–91. Retrieved from: http://www.sciencedirect.com/science/article/pii/S2214914714000385
Ross, Kirk. What Really Happened at Wanat. Proceedings Magazine, July 2010. Vol. 136/7/1.289. Retrieved from: http://www.usni.org/magazines/proceedings/2010-07/what-really-happened-wanat
Smith, Herschel. The Captain’s Journal. Multiple posts on Wanat linked to his Battle-of-Wanat category. Basically, Hersh has beaten all this ground years before (and we’ve even cited his reports here, before). Retrieved from: http://www.captainsjournal.com/category/battle-of-wanat/
Windham, Jeff. Fire To Destruction Test of 5.56mm M4A1 Carbine and M16A2 Rifle Barrels. Rock Island, IL: Engineering Support Directorate, Armament Research, Development And Engineering Center. September, 1996. Retrieved from: http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA317929 (Abstract: http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA317929).
Witherell, Mark, & Pflegl, George. Prediction of Propellant and Explosive Cook-off for the 30-mm HEI-T And Raufoss MPLD-T Round Chambered in a Hot Mk44 Barrel (Advanced Amphibious Assault Vehicle – AAAV). Watervliet, NY: Army Research Laboratory/Benet Labs, March 2001. Retrieved from: http://www.dtic.mil/dtic/tr/fulltext/u2/a388280.pdf
The third day of the Ky modern gun season started out cold and dreary with light rain mixed with sleet. All morning I had set around debating with myself on if I should suffer the weather , the climb up the mountain and the hours and hours of boredom. I had stopped hunting deer over 15 years ago. I found after killing several, it seemed more work than fun. The difference this year was I had in my hands the new Colt 901 M.A.R.C. carbine with the new modular rail. The 7.62 gun is a new variant of the LE901 and was sent to me just a few days prior for T&E and writing about. I REALLY wanted to do something special with it and since season was so close. I decided it would be nice to be possibly the first person to take a head of big game with it. Around noon I decided to try it again for the fifth day after all.
I had been to the same area over the last few days and knew there was deer in the area. While I do not deer hunt anymore, I do small game hunt and shooting squirrel is a favorite fall pastime for me, I had noted the heavily used game trails in the area I like to shoot the tree rats and it had passed my mind to tell my friends who do still hunt deer about it and maybe they could use the area. They lust for the horns more than I ever did, The area also had the advantage of being 3/4 of the way up a mountain and there is no way an ATV could get to it. Now a days, hunters are lazy in my areas. They will use the 4-wheel drive ATVs to drive to the toilet if they can get it through the door. Most will put out feed for the animals year round and have a tree stand that set above the feeding section. I am told by hunters with a straight face that none of that makes it easier to kill the deer though. I often add. “then why do you do it”? I never get an answer. I hunt from the ground by walking/stalking and watching over areas they will travel or eat. If I can get on a large rock I will, but never a tree stand. I do not think of it as a real hunt to me, nor would I feel any bit of real accomplishment if I shot one from a tree stand. That is just my feelings and opinion on the matter, not a rag on anyone’s system.
I knew the spot would be free of the average hunter since no ATVs could get to it. And, no ATVs means no one would be willing to climb up a mountain carrying a tree stand. So that means no other hunters. Never mind it is my own private land since locals rarely let something like private property stop them,
I was lucky in that it had rained all night and the leaves had become wet and soft. The days prior had been warm and dry and I had spooked deer in the area just trying to sneak close to where I had in mind. No such problem that day,.
The mountain is a pretty good climb, so it took me a while to get to where I wanted to be moving slow enough not to spook everything within a mile. Finally I arrived and leaned up against a large beech tree, and pulled the gortex hood over my head and got out a paper back book. In my experience its best to have something to help with the boredom. I settled the rifle across my lap and double checked to make sure a round was chambered. The ammo used this trip were loaded with the excellent Barnes Triple shock X solid copper hollow point. The 308 bullet in this load being 165 grains, One of the perks of the TSX is the 3 rings cut down on surface and the bullets will get slightly higher velocity with less pressure and cut down on copper fouling. I use the TSX bullets in everything I intend to shoot something live with. I use them for deer, varmints and they are my choice in my personal self defense 5.56 and .45ACP rounds.
To my surprise I had not been setting 20 minutes when I heard movement on the opposite hillside to me. I was setting almost all the way to the top of a finger that runs off a ridge line and another finger ran parallel to the one I was on. I could see most of it and down the middle of the two. It took me a few seconds to spot a doe. Not being able to take a doe in the county I live in, I had to watch it pass. To fight the boredom I watched the deer through the optic for a while I thought about what a great shot it was giving me. The scope used is the Leupold 3x-9x TS-30 with a Mil-dot and it was clear on the over cast rainy day. Out of the corner of my eye I saw a small bush shaking, I moved the scope to see what the deer was and to my surprise it was a buck! Instantly I was tensed up and excited. It had been 16 years since I last saw a buck while hunting for one. And with the new gun in my hands just for this reason I had to take a second or two to calm myself and not get a little too excited.
The next three hours were torture. The game was 240-250 yards away and I could only see them through small under growth and tree branches. No clear shot I was confident to take presented itself. There is not such thing as a “brush busting” bullet. Even the smallest twig can send your bullet in any direction other than what you want and I was not willing to try it out anyway and mess up the chance with this new Colt. the buck and two doe walked around in a large circle. About the time I thought I should have risked a shot, I would hear a grunt or snort and around they would come again. it was agony I had to admit. I wanted to kill the thing and it was getting cold. The wind and sleet had gotten worse and I had my gloves in my pocket. I took them off on the way up so I would not sweat too much and no the metal of the gun was hard to hold in the cold weather. I could not risk the noise and movement to get them out.
About 90 minutes before dark I saw some rapid movement near where I first spotted the buck and directed the optic that way. I almost laughed out loud as I saw the buck mounted on the doe doing his level best to make another young buck, This went on a while as I watched trying not to feel like a pervert. The doe would sometimes tire and move off a bit and the buck would walk after her, At this point I knew I could have done just about anything and gotten away with it. When the rut is on, the bucks don’t care if you detonate a nuke. They only got one thing on their mind and its not worrying about getting shot. If don’t deer hunt, imagine two teenagers on a date looking for some place private.
I watched this bit of romance for a while as the two slowly started going up the hill and toward a large amount of brush I knew I would lose them in as the sun was going down. I knew I was running out of time. At last the buck started humping the doe and they moved into an area open enough for me to figure now is as good as it is going to get., As he was on top of her, I put the Mildot cross hairs on his shoulder and fired. it was almost a 250 yard shot and was exactly what I was hoping for. I have always been a long range shooter so the short 40 yard or 10 yard shots always felt like a let down to me. A rifleman needs some distance to add to the sense or pride from making a clean kill and fine shot. Nothing shows skill like a clean hit at some real distance.
As soon as I fired I listened and did not hear any noise of movement or running and not even stumbling and branch breaking. I knew he was dead and dropped instantly. I looked through the scope and saw a few legs twitching, I set for a few seconds with the intentions of letting ti die where it is but it seemed to be trying to get up, I started to move to the down animal but it rolled down the hill crashing through brush. It did this three more times until it came to rest in the middle where the water runs off. I walked down to it and saw I had hit it a little high because of the angle and severed his spine, He had been trying to move but was only getting his upper neck going enough to cause him to roll down hill. He was dead but just did not know it yet. I almost felt bad about shooting him during his romantic love making, but decided if you gotta go……
I rolled him over and was pleased to see he was an 8 point, This was the biggest rack I have taken, the next largest being a 6. I was never a trophy hunter and never will be, so this was very nice for me. I am just as happy with a button buck, a spike or a doe. The way I hunt is not easy and getting one while being on the ground with them and not baiting them with feed all year is hard, and anything killed that way is something to be proud of in my mind. This was icing on the cake,
I got him gutted after I snapped the above picture ,filled out the tag for it walked off the mountain and got some help to drag him the mile off the hill. Two fine neighbor hood teenage boys came and dragged it off the hill for me. Finally well after dark, we got him in. I gave the meat of the animal to one of the boys family that needs the food. I sawed the horns off to keep for myself. The memories of the earned kill , a fine rifle and fine shot are all I need to enjoy it, I am not much for having the head mounted any more.
The Colt 901 MARC was all I hoped it would be for this hunt. The lighter weight made it easier to carry straight up hill all day. The original LE901 was a little heftier than this new model. Not a lot, but when you are carrying a lot of stuff up hill, it helps a lot more than you think. Fighting though low brush is a lot easier with the 16 inch barrel as well. Having the handling of a carbine but in 7.62 was a nice feature. I hunted with a 5.56 for years and have taken deer with it, the 7.62 is not something you have to have. The 5.56 is just fine for deer sized game as long as you use a decent bullet. I don’t want to give the idea I think the 556 won’t do this job, so keep that in mind. Had this gun been some kind of 556 I would just as happily used it with the same amount of confidence.
I did not use anything but the factory trigger. The milspec trigger is just fine. People who say you have to have a match trigger to make precise shots are just not that good of shooters, Yes it helps if you are already a decent marksman, but for most it is trying to buy skill with equipment, I used much maligned factory milspec trigger to make a 240-250 yard one shot kill. Practice. The stock was also the stock that come with the gun
You may note the 20 round magazine in the picture. In some states, and Ky being one of them, you can not have more than 10 rounds in your gun. I used a small block of wood to block it off myself for the hunt. It held 9 rounds while blocked off in this way. I wanted a little wiggle room in case some how it moved in a way to allow one more round and I got checked by the conservation officers. That would have been a bad day. So without a factory 10 round mag in hand in time for the hunt, I blocked it myself and went to the side of caution.
The ammo I used was the Federal premium 165 grain Barnes TSX ammo. The TSX bullets are always my choice. The will expand at even low velocity and retain all their weight. The bullet went clean through the deer shoulder and spine from 250 yards and shot through. they are superb bullets, Accurate and always perform as advertised. You can handload them or buy them as factory ammo. Normally I would hand load them in what I want but did not have any .30 cal TSX on hand when I got the gun, so I used factory this time.
The optic was all I could ask. The nice compact TS-30 A2 optic was small and light and did not get in the way or snag on anything. You do not need a huge scope with a huge objective, You also do not need a large amount of magnification. 3x-9x is plenty , IF the glass is quality and crisp and clear. You can make a very long range shot with low magnification but you will be hard pressed to make a very close shot with high X. It is always best to leave the optic on its lowest setting when moving since you may get a close shot on a moving target. You can always zoom it in later. And if you do see a far shot but do not have time, You can still make the shot at the low setting, If you think otherwise you just have some kind of mental block. The optic has an illumination feature, but I did not have a battery in it. When it got close to dark I really missed that glowing red cross hair. It is indeed a handy thing to have when it starts to get dark and you are holding a black cross hair on a a dark animal in the shade. In my opinion the illuminated cross hairs is never a waste on quality optics.
After 16 years I finally bagged another deer. It was a long hard hunt and I feel it was earned and it gives me a great amount of satisfaction. All of the things came together from scouting during small game hunting, to the hike in, to the marksmanship and the final shot with a fine rifle. If not for the rifle I would not have even went hunting deer again, the Colt 901 MARC may be meant for other things, but it is also certainly a fine hunting rifle for the modern rifleman.
This is not the actual review of the new Colt 901 MARC but a bonus side test. The start of the full review will start this week with the first part of the full testing and review coming soon after
A few weeks ago we got contacted via our facebook page by Front Range Survival about their products. http://www.frontrangesurvival.com/
A few days later I got an item from them to test out and review. As you can see in the picture of above it is is a fire starting fire rod. The handle/lanyard if 14 feet of military grade parachute chord in hunter orange for ease of locating it once you drop it in the grass. Or, if you need to make a shelter, signal help or first aid use in case of things turning really bad.
I and a friend spent the last few weeks working with this thing and it is the best one of these we have ever used. We have looked at fire starting rods and kits over the years and had a lot of frustration and failure with kits that are supposed to be the best. Not with this one. It sparks immediately and the sparks are large and hot. The first time we went to use it I crumpled up some dry leaves and some very lightly damp grass. It took three swipes of the knife on this thing and we had a very good flame going that we turned into a fire in no time. It was a cool damp day with a little wind, but the sparks from this thing got the job done. It is really impressive.
I use the tool with the USGI knife I also threaded with a lanyard. The flat screw driver “blade” made it fast and easy and the two can be wrapped up together.
the Front Range tool is seen here with the utter failure that is the Bear Grylls fire starting tool kit. I have seen Mr. Grylls use this kit on TV many times and make it look easy. But I will tell you right now, we spent many hours in the best conditions trying to get something going with it to no avail. It just does not compare, The sparks are tiny and pathetic. It looks good and is a great idea in theory but it just does not hold up to the FRS piece.
On the website, the company describes their thinking and the tools as follows.
“We set out to make the best survival gear on earth. Everything we carry has been field tested by us.Its our gear… and now it can be yours.
Our flagship products are Fire Starters.”
They had a real winner with this tool. I am by no means and expert survivalist, but I know quality when I had it in my hands. And when some one as clumsy as we are, can work something so fast you know it is good. As my friend says. this is the kind of quality tool that makes a person get excited and want to practice their field and bush craft more often. I agree with that statement absolutely. Everyone who tried the fire starter was instantly impressed and wanted one, Not many people I personally know has tried one of these that works as well.
After talking about the tool for a while we determined a nice little kit to put together with it for signaling and making fire while on a hike or for whatever reason.
We gathered some things together and found a spare MOLLE GP pouch it would all fit in and leave room for more as we deemed might be needed and of course we can remove or add to as the situation may dictate. The idea being to have one on you, in a pack or left in your vehicle. The pouch as seen above comes with the knife with lanyard. The FRS fire started and some cotton and dryer lint ( which with the FRS tool makes fire as fast as a lighter) A signal mirror and a Military pilots cloth signal panel. Some medical gear and of course a lighter or two will be added as well as some other odds and ends. But this is a good starts so far in our minds.
The Front Range Survival fire rod is heavy duty and the pictures don’t seem to show just how big it is. It is not huge or unhandy but you get enough to do the job. It will last a long time.
I wrapped it up in a sealed bag with some material to help with the fire and cinched it with a rubber band. This will let it easily fit in a single AR15 mag pouch and still have some room left over. You can store one about anywhere.
A lot of people are always looking for more effective survival and outdoors tools. This is certainly a winner in my opinion, If you do anything or go anywhere you may find you need a fire, this thing is worth having. I would not go on an over night hunt without one of these now. If you want one, the link to the amazon page is below. You can also read the reviews from buyers there as well.
It is a dangerous world out there, and as uncomfortable as it is to think about, the current state of the country means not every one is armed to step up to defend the most helpless among us. With that in mind and the recent atrocities, we decided to do some testing on something often suggested as a means for children to protect themselves in case the unthinkable happens and no one is around with a gun that could otherwise stop the threat.
You may have heard or read about the idea of kids using a book bag as a means to trying to stop a round from an active shooter. I have even read some talking about bags lined with soft armor. After my tests last year of seeing what common rounds would do inside a house, and the difficulty or even rifle rounds penetrating books and some tests shown on Best Defense years ago by Rob Pincus, I can attest to the ability of books to stop about any rifle round.
For the test, we filled a pack with some real text books. from a relatives left over college semester. and some magazines to simulate a note book of just paper. Nothing else was added, not soft armor, or plates sewn in to give it any more help to stop a round. This was meant to see how it would do if books and some nylon was all you had.
Rounds used were 5.56 in M193 and M855, 9mm using NATO ball and .45ACP ball as well as 12 gauge 00 buck, slugs and the ever popular ( though absurd) birdshot. Five rounds of each got fired into the bag to see how it would penetrate. We could not set the Q target against the bag without knocking it down or tearing it every shot, so we settled on setting it a few inches away. The test was not meant to show any blunt trauma, just penetration. Again, for those who will complain.. this was not scientific, nor does it prove anything as a hard fact, thought we feel it is useful and gives plenty to think about.
First up. was 9mm ball, NATO pressure ammo, Fired from about twenty feet, as if the victim was running away. We later found even contact shots had the same result. the 9mm failed to penetrate beyond a few inches of book and barely moves the bag.
One manages about 3 inches, but most stopped inside the book. We fired another five rounds of 9mm to the same result. Those that did not stop in the books deflected at harmless angles. We both expected better performance since the hotter 9mm load is often touted as being a decent round for penetration.
Next up was the .45ACP 230 grain ball ammo. Shot from the same distance
Same results from the 45 with just a little deeper penetration into the books but with more damage to the books by this point. The bag did flop and move more violently, and for a second we thought one may have gotten through, but, once again, nothing got anywhere close.
Above you can see the results of the .45ACP ball rounds on the books. Several 45 ball rounds were found in the books with almost no deformation.
Next up was the 5.56 fired from standard 16 inch Colt 6920 with 1/7 twist barrel from the same distance as the pistols.
To my absolute not surprise at all. Nothing got even close. Equally ineffective was the M855 round. Both rounds fragmented inside the books and nothing big enough to even speak or was recovered once we started to sift through the remains of the bag and books.
Next we fired the 12 Gauge with the 00 Buck. Looking at the pictures with no back ground it may look impressive, but the pictures out of context tell a lie. The dead center hit was from one of the pellets going high and missing the books in the bag. Sure this would happen in real life, but the point was to see what would make it through books being used as protection. Obviously a head shot would render it all a wasted effort, but that is not the point of this test. The other “hits” resulted from deflection. The buck hit the books, flattened and deformed and went around and out the sides. There was no real penetration. I am not really sure how to label this in contest of the test since none of the made it though the protective layer of books proper, but hits did get on paper. Something to think about, and it may be a fluke because of the harder book covers and thickness, Obviously there is not real way to predict anything a round will do after it hits anything other than air.
Next up was the punishing police slugs from the 12 gauge. five rounds from the same distance as the rifle and pistol. Nothing at all on paper. The bag sure looked like it felt it though. Damage to the body even from the slugs not making a hit would be significant in my unlearned medical opinion. But I suppose it still beats getting a 12 gauge slug through the back.
Lastly was every moron’s favorite home defense shot gun round. Birdshot. Nothing even got mush past the nylon bag, but as soon as the shot hit the hard cover book, they all deflected. lost most of its energy and followed the inside of the bag around an came out the other side, I guess you could call it a “hit”, though the pellets did not even go all the way through the cardboard, and did not even do much to the books. The shot did scatter everywhere once hitting the harder books and then deflecting. Since it did not penetrate even the soft cardboard, I have no idea what it would look like on a human. My guess is the skin would be broken and some bleeding and pain, but not enough to kill a grown person, though it would still be terrible on a kid. Of course the further away the person got from the shooter, the even more useless the bird shot would become. Another 20 feet and maybe safety glasses would be all you needed after a shot to the books and bag, but still its something to consider.
After testing the pistols and rifle rounds again at contact distance and seeing the same results, I took the books apart and we sifted through the remains out of being curious. The closer fired 45 rounds seem to deformed a bit but not much, no fragmentation to be sure. Even less from most of the 9mm, I believe most of the damage to both was from fired rounds hitting already embedded buck shot or other bullets. The lead buck and slugs became blobs of every shape and size with the 00 buck flattening out but still looking in some what original condition while the slugs looked to have suffered great damage.
Could you use a bag full or books for a last ditch protection? Absolutely. If you had nothing else and got caught in the open, you sure could do worse, Children should be taught to try to use the bags for cover, maybe even being coached to snatch a loose one up and wear one on the front and back while trying to make an escape if possible if it was not so heavy it impeded speed.. Stack books behind a door or desk being used to hide, turning it into cover would also be a great idea. The ideas are many and I will leaver that to the people more qualified than I am to advice you on your kids protection. But, just like strategically placed books and shelves in the home to protect you from gun fire, the books in a pack will do the same if it came to that.