Tag Archives: Zeroing

When the Army Resisted the M16A2, Part 1-3

Today  is our traditional day of re posting some of the best articles of our friend Kevin O’Brien  better know as Hognose by his many admirers and readers of his website weaponsman.com. Kevin left us too early  in spring of 2017 and we repost his work here to honor him and preserve his work.

 

By Kevin O’Brien

The M16A2 was adopted by the Marines in 1983, and then by the Army three years later, but all of its development was done, largely on a shoestring, by the Marines.

For example, the finger bump on the A2 pistol grip? The very first prototype was built up by a Marine officer on an A1 grip, using plastic wood or body filler! Most of the modifications to the A2 were aimed at:

  1. Increased practical accuracy;
  2. Increased effective range;
  3. Increased durability; and,
  4. NATO compliance (adopting a NATO round equivalent to the FN SS109 round).

In a brief overview of the service life of the M16 series for American Rifleman in June, 2012, Martin K.A. Morgan encapsulated this history well:

In November 1983, the U.S. Marine Corps adopted a product-improved version of the M16A1 chambered for the 5.56×45 mm NATO round. The new rifle was called the M16A2 and it differed significantly from its predecessor: improved rear sights, a brass deflector, a heavier barrel and 1:7-inch rifling were among the changes. The M16A2 also replaced the M16A1’s “AUTO” selector setting with a “BURST” setting delivering three rounds with every trigger pull. The Army followed the Marine Corps’ adoption of the improved rifle in March 1986 when it ordered 100,176 M16A2 rifles from Colt. In September 1988, the U.S. government placed an initial order for 266,961 M16A2s with Fabrique Nationale’s North American subsidiary, FN Mfg., Inc. of Columbia, S.C. Late the following year, when 57,000 U.S. military personnel conducted the Operation Just Cause invasion of Panama, the M16A2 was used in combat for the first time.

For practical accuracy, the A2 had new sights, with a square front post; for range, a new round with a heavier bullet, and new rifling to match; and for durability, new stocks and handguards and significant metal reinforcement in the lower receiver’s weak areas, the pivot pin bosses and buffer tower.

The rifle was not without controversy in the Army. Indeed, contractors for the Army Research Institute for the Behavioral and Social Sciences examined the rifle and concluded that, as their paper’s abstract notes:

[U]se of the M16A2 rifle by the Army would be extremely problematic, a-fact due, in part, to the vast differences between the marksmanship training philosophies of the Army and the Marine Corps.

(The paper is here: http://www.dtic.mil/dtic/tr/fulltext/u2/a168577.pdf)

The Army had been researching improvements to the M16A1 for years, but hadn’t actually implemented any. In the foreword to the Army Research Institute paper, the word “problematic” crops up again and one gets the sense that the problem was this solution was Not Invented Here, and moreover, not developed the way the Army wanted to develop one.

Referring to earlier research, they wrote:

A detailed evaluation of M16Al performance was conducted to determine adequacy, peculiarities, etc. The findings clearly indicated that the M16Al was an adequate combat rifle; however, many shortcomings were identified that should be addressed in a new rifle or any rifle Product Improvement Program (PIP).

They considered that the improvements in the A2, listed below, were suitable only for the peculiar circumstances of Marine Corps service.

The Marine Corps test results stated the following advantages for the PIP [Product Improvement Program -Ed.] rifle:

  • Ease of training (handling and ease of sight movement).
  • Improved safety (no hazard when adjusting elevation on the rear sight even with loaded weapon).
  • Increased effectiveness at long ranges (more hits, better accuracy, and greater penetration).
  • Improved handling characteristics and durability in hand-to-hand close combat.
  • Reduced barrel jump and muzzle climb during automatic and rapid fire.
  • Increased contrast and less glare with square front sight post.
  • Stronger, more durable and improved grasping characteristics of front handguard.
  • Stronger barrel with quicker twist to take advantage of increased effectiveness provided by new ammunition.
  • Improved sighting characteristics providing quick target acquisition for moving targets and better detection of targets in low level light conditions at close ranges, and more accurate long range fire by use of two modified rear sight apertures.
  • Increased ammunition conservation and more effective use of ammunition with burst control device.
  • Conformity to human factors standards by lengthening stock (alleviating bruised eyebrows, noses, and lips).
  • Stronger, more durable stock.
  • Stronger, more durable buttcap which also reduces slipping on the shoulder during firing.
  • More controllable and comfortable pistol grip contoured to the shape of the hand.
  • Improved brass deflector which protects left handed shooters from hot ejected brass casings.
  • Can use NATO type improved ammunition (XM855) which provides improved performance and penetration at long ranges.

The Army evaluators were impressed by that list of solutions, but thought they all traced back to four specific USMC objectives or requirements:

The above list of advantages is very impressive. It appears that the rifle meets the primary requirements stated by the Marines:

  • A sight adjustable to 800 meters.
  • A bullet with better accuracy at 800 meters and the capability to penetrate all known helmets and body armor at ranges of 800 meters.
  • A rifle with more durable plastic parts and barrel which will take a beating during bayonet training and extended field exercises.
  • The replacement of the full automatic capability with a burst mode which fires a maximum of three rounds with each pull of the trigger.

…but they thought that the requirements were too Marine-centric.

The list, however, represents the objective and subjective evaluation of Marine Corps personnel who are emphasizing the most positive aspects of rifle characteristics as they pertain to envisioned Marine Corps requirements.

This is the first of a three part series. In the second part, tomorrow on WeaponsMan.com, the Army contractors damn the A2 with faint praise and list a litany of A1 shortcomings that they believed that the A2 did not resolve. In the third part, the modifications that they suggested in lieu of or in addition to the A2 mods are enumerated.

As it was, the contracting officer’s representative approved the paper in February, 1986. In March, and probably before any of the responsible officers read the paper, the Army went ahead and adopted the M16A2, just the way the Marines had shaken it out.

That makes this paper a time capsule.

When the Army Resisted the M16A2, Part 2 of 3

The M16A2 was adopted by the Marines in 1983, and then by the Army in 1986. Shortly before its adoption, an Army contract analyzed the M16A2 — and found it all wrong for  the Army. The report is here: http://www.dtic.mil/dtic/tr/fulltext/u2/a168577.pdf

This is the second of a three part series. In the first part, yesterday on WeaponsMan.com, the Army contractors noted the specific solutions implemented on the A2 and the problems the Marines solved thereby, but complained that the problems and solutions were too USMC-specific. In this part, we’ll discuss just what they thought was wrong about the Marines’ product. In the third part, which we’ll post tomorrow, we’ll list the modifications that they suggested in lieu of or in addition to the A2 mods.

M16A1 (top) and M16A2.

As we recounted in yesterday’s post, the Army let a contract to analyze the Marines’ product-improved M16A1, originally called the M16 PIP (Product Improvement Program but in November 1983, type-classified as the M16A2. Did the A2 meet the Army’s needs for an improved rifle? The contractors recounted 17 improvements in the A2 versus the A1, and traced those improvements back to four or five fundamental goals of the Marine program: more range, accuracy and penetration at that range, more durability, and a burst-fire capability in place of the full-auto setting.

The Army contractors recognized what the USMC had done — and damned it with faint praise.

The M16A2 rifle was developed and tested by the U.S. Marine Corps. The purpose of this present analysis was to evaluate M16A2 rifle features as they relate to U.S. Army training and combat requirements. It was found that the M16A2 did not correct major shortcomings in the MI6Al and that many M16A2 features would be very problematic for the Army. Accordingly, this report provides several suggested rifle modifications which would improve training and combat performance.

The A1 shortcomings that the paper’s authors thought went unameliorated, or were worsened, by the A2 included:

  1. 25 Meter Setting: The M16A2 does not have a sight setting for firing at 25 meters, where zeroing and most practice firing occurs.
  2. Battlesight Zero: The M16A2 does not have a setting for battlesight zero, i.e., 250 meters.
  3. Aperture Size: The M16A2 probably does not have an aperture suitable for the battlesight, e.g., the single aperture used for most marksmanship training, the record fire course, the primary aperture for combat, etc. The 5mm aperture used for 0-200 meters is probably too large and the 1-3/4mm aperture used for 300-800 meters is probably too small.
  4. Sighting System: The M16A2 sighting system is too complex, i.e., elevation is changed three different ways, leaving too much room for soldier error.
  5. Sight Movement: Sight movements on the M16A2 result in changing bullet strike by different amounts; .5, 1, 1.4, and 3 minutes of angle (MOA)*. The sights intended for zeroing, .5 and 1.4 MOA, are not compatible with old Army zero targets or the new targets being fielded.
  6. Zero Recording: The M16A2 does not have a sighting system which allows for easy recording of rifle zero. Also, the zero cannot be confirmed by visual inspection.
  7. Returning to Zero: The M16A2 does not have a reliable procedure for setting an individual’s zero after changing sights for any reason, e.g., using MILES or .22 rimfire adaptors.
  8. Night Sight: The M16A2 does not have a low light level or night sight.
  9. Protective Mask Firing: The M16A2 has not been designed to aid firing while wearing a protective mask.
  10. Range Estimation: The M16A2 sight has not been designed to aid in the estimation of range

Let’s consider those, briefly. Note that every single one of those objections relates to the sights. There are no complaints about the other Marine improvements (not even the hated burst switch). Most of the sight squawks were because the sight was different from the sights of the A1, which were pretty much as Stoner, Sullivan et. al. designed them circa 1959 (the earlier AR-10 sights are different, but the later AR-15 prototypes and their descendants all used something extremely close to the M16 and M16A1 sights. (The USAF/USN M16 and the Army/Marine M16A1 differed only in the absence and presence respectively of a forward assist). Even the protective mask issue is basically a sighting problem — with the then current US M17 gas mask, the rifle had to be held canted to use carrying-handle based rear sights.

Complaints 1-5 relate only to the M16A2 sights, but 6-10 are just as applicable to the then-issued Army M16A1.

Even at the time, it was clear that optical sights were better than irons — scopes for distance and red dots for close-in work. Army special operators had already tested — on the flat range, in the tire house, and on the two-way range — such early red-dots and both-eyes-open sights such as the Single Point and the Armson Occluded Eye Gunsight (OEG). In the early 21st Century, universal optics would end the long run of the M16A2, and sweep away all these problems the 1986 Army contractors worried about. But there was no way to predict that in 1986, not with any certainty.

And that’s Part 2 of our story. Tomorrow, we’ll cover the modifications to the M16 that the authors recommended in place of the A2

When The Army Resisted the M16A2, Part 3 of 3

The previous two stories set the stage, for a look at a report drafted for the Army Research Institute for the Behavioral and Social Sciences the Army was still pursuing the “best” (an upgraded M16 meeting all Army objectives) instead of the “good” (the M16A2, which was developed and revised to meet Marine objectives). Of course, we all know the spoiler aleady: the Army accepted the Marine M16A2 as is, leaving the report as an orphaned artifact. The report is here: http://www.dtic.mil/dtic/tr/fulltext/u2/a168577.pdf

Colt factory shot of the M16A2. The A2 was developed by the USMC, but was manufactured by Colt and FNMI.

This is the third of a three part series. In the first part, Thursday on WeaponsMan.com, the Army contractors noted the specific solutions implemented on the A2 and the problems the Marines solved thereby, but complained that the problems and solutions were too USMC-specific. In the second part, posted yesterday, we discussed just what they thought was wrong about the Marines’ product. In this, third, part, we’ll list the modifications that they suggested in lieu of or in addition to the A2 mods.

Most of the Army’s problems with the A2 related to the burst mechanism, and the sights, especially the complicated rear sight. (This is actually an A3/A4 or M4: note the knobs, left, for removing the carrying handle. The A2 handle was forged as part of the upper receiver.

Reliability

We should note that the Marines’ tests, as reported in this document (p,7), demonstrated significantly lower reliability, and increased fouling in the A2 compared to its older brother. These tests are suspect because the early lot of XM855 used was considered bad ammo, but the M16A1 did outperform the A2.

Thirty Ml6A1 rifles firing 26,010 rounds of M193

Failures to fire – none
Failures to feed – 3 (Not locking magazine in place)

Thirty M16A2 rifles firing 26,010 rounds of XM855

Failures to fire – 52 (27 – bad ammunition) (25 – mechnanical [sic] malfunctions)
Failures to feed – 3 (Improperly loaded magazines)

Those failures to fire that were not attributed to bad ammo were thought to be caused by the A2 trigger system’s Achilles’s heel, the burst trigger mechanism. The A2 performed even worse in a cold weather test, but again, it was with the questionable ammunition, and many of the failures to fire were also laid at the feet of the burst mechanism.

The report has an interesting discussion of the burst mechanism and its rationale in Marine, but not Army, small arms doctrine:

The M16A2 has less combat capability due to the elimination of full automatic fire. Full automatic fire enhances the ability of Army units to clear and defend buildings, to conduct final assaults on enemy positions, to defend against an enemy final assault, to conduct an ambush, to react to an enemy ambush, to engage an enemy helicopter or fast moving vehicle, etc.

While the Marines claim greater accuracy and conservation of ammunition for the 3-round burst control, no data were generated during the test to support these contentions and no supportative [sic] data are known to exist.

Also, it should be noted that room-to-room fighting was conducted with blanks, no close-in firing was conducted, no firing with short time limits was conducted, no firing at aircraft was conducted, etc. In other words, for all of the automatic/burst firing conducted during the test, a semi-automatic mode of fire would have probably resulted in a greater number of target hits.

Finally, to be given very serious consideration, is the fact that the burst control requires nine (9) new parts in the lower receiver, evidently contributing to the large number of weapon malfunctions during testing of the M16A2.

They also took issue with the heavy barrel (“heavy in the wrong place”), the twist rate (preferred 1:9), stock length increased when even the A1 stock was too long for small soldiers, and the fast twist’s incompatibility with the .22 subcaliber system.

The article includes an extensive comparison of the pros and cons of Marine KD vs. Army Trainfire marksmanship modalities. These training differences result from the different combat envelopes for the rifleman: the Marines need to engage with rifles in the 300-to-800 meter space, because they don’t have the supporting arms that the Army can count on, at least, not in the same quantity. A unit that must fight with just its organic weapons needs to get the very most out of these weapons. The Army of 1986 did not consider a 500 or 600 meter target a primary rifle target, but a crew-served-weapons target.

In the end, the recommendations the contractors made were mostly about the sights. They put their recommendations in a table with the M16A1 and M16A2 stats. Since the latter are probably familiar to most readers, we omit them now to save time, and just show the contract recommendations.

Item Recommended
Front sight (day) Fixed blade, 0.090″
Front sight (night) Luminous dot on each sightguard
Rear Sight (day) single 2mm peep. A single elevation knob marked for 200, 250, 390, 25, 400, 500, 15, 600, 700, and 800 meters. Windage knob at rear. Each click equal to 1 MOA
Rear Sight (night) Two luminous dots on upper portion of receiver (or a single flip- up luminous dot located forward of the carrying handle) are aligned with front dots for shooting at night
Zero Recording Yes
Zero Inspection Yes
25m setting (day and night sights) Yes
Mechanical Zero Yes
250-m battlesight Yes
Firing mode Semi and Auto
Barrel 20″. Slightly heavier than A1 at receiver and mid-barrel. 1:9″ twist
Handguard Same as M16A2 except held in place with a securely fastened ring nut to provide rigidity.
Buttstock Same material as M16A2. Same length as M16A1. Option for adjustable length.

There are several interesting observations to make here. First, the contractors recommended that the Army make changes that would decrease the mechanical accuracy of the proposed M16Ax relative to the Marines’ A2. Specifically, these changes included the wider fixed front sight blade, the 1-MOA adjustments on the rear sight (A2 offers ½-MOA), and arguably the simplification of the rear sight. The trade-off was simplicity and ease of training, instead of superior bullseye performance.

Second, some of the proposals would definitely improve the utility of the firearm, including restoring the short stock, or replacing it with an adjustable one; increasing the barrel diameter towards the chamber rather than the muzzle, thus improving sustained fire accuracy and reliability; reverting to automatic fire from the burst mechanism (which also has side benefits, in improving the trigger’s feel and consistency). The night-sight proposal was truly ingenious.

Third, in some of these road-not-taken proposals, the Army was reverting to the original AR-10 design and rejecting changes that were largely imposed on the AR design by the Army in the previous decade. These include the rigid fastening of the handguard, and the fixed front sight blade.

Finally, these proposals were almost the last gasp of the iron-sighted military rifle. As this  document passed from the contracting officer to file cabinets across the service, without action, special operators were already wringing out scopes and single-point sights, and a few visionaries were already arguing that the day of the iron sight had run its three centuries, and was now at an end. A new generation of optical technology was eliminating the two objections that had kept optics off the rifles of most soldiers: less durability than irons, and slower target acquisition. Many men’s efforts went into winning over the Voices of Experience who still said “no” to anything with a lens, thanks to memories of Uncle Joe’s elk lost because his scope fogged up, or the VC that got away because somebody attached an unauthorized 4×32 Colt scope to the carrying handle of his M16.

About Hognose

Former Special Forces 11B2S, later 18B, weapons man. (Also served in intelligence and operations jobs in SF).

Putting the M1A in perspective.

Not that long ago I had a friend ask me about the M1A, to which I replied, “Don’t tell anyone because I have a reputation to uphold, but I actually like the M14.”  It was right at that moment that I was finally able to piece together my thoughts on the strengths and weakness of the M14 style rifle.  Now I am going to use the terms M14 and M1A interchangeably to refer to both the military weapon and the semi auto copies of it.

I love the M1Garand, and I see people buy them and love them too.  Someone gets a Garand and they know they are getting a piece of history, and a good rifle for shooting with iron sights.  They know they can use it in field positions and off the bench.  A person buying a Garand is not expecting to get the ultimate CQB Sniper Rifle for shooting sub-MOA 1000 yards.

We Americans often take great pride in our gall to push things past practicality and the M14 is the perfect example.  Historically American’s have always loved accurate combat rifles, and the M14 is no exception.  But there is a big difference between a combat rifle and a precision rifle.  The M14/M1A has great iron sights and is a fun gun to shoot.  But when you start try to turn it into a scoped precision rifle it just doesn’t make the grade.  Simply put the handling and practicality of the M14 dies when we try to modernize it.

Optics on the M14 end up at awkward heights.  The various ways to improve accuracy are significantly more expensive and harder to maintain than on more modern rifles.  If you have a match M1A with a bedded stock each time you remove the action from the bedding you wear and risk damaging the bedding.  I saw a great quote some years back from an Army Solider issued a M14 EBR.  He explained that with that weapon system being used in the desert he was suppose to properly clean it after every time he fired it.  Cleaning it properly would involve removing it from the chassis, which would then require re-zeroing.  Re-zeroing it would then necessitate cleaning.

That is a pretty extreme over the top example.  M1A are rather accurate rifles, and can be made more so.  But to get modern semi-auto sniper type precision out of a M1A is going to cost you a good deal of money and time and will require more maintenance than other alternatives.  You generally don’t see people try to turn FN FALs or rack grade G3s into precision rifles, same applies for the M14.

But, if you are looking for a good rifle to shoot with iron sights on the known distance rifle range off the bench and in field position the M14 is great at that.  I just don’t recommend buying a M1A thinking you can build the ultimate sniper by slapping a scope on it, or expecting to use it as the as the perfect CQB weapon with a red dot9.  Don’t forget the M14 is longer than a Garand.

Just like the Garand, the M14 is a piece of Americana.  A fun piece of equipment from it’s time, but that time has passed.

Scattered Shots 7-30-2018

Due to having to take my Father to a doctors appointment today and some other things, there won’t be any detailed technical article or historical  writing.  Instead   I will be letting my mind wonder a bit and share a few things that have caught my interest over the years.  I hope it will be a fun post for all.   If there is any “theme” for today’s post it wold indeed be scattered shots.

A few years  ago I ran across the pictures taken during the  war in SE Asia.  They are from a news article reporting on the young girls of RVN training to fight the communists.   When ever I rear or see a video on youtube of some hot, big name expert firearms trainer ex-marine SF trooper advising people about how hard it is to control the recoil of  the .45ACP and the M1911. I think of these pictures.  Having spent  many years around Vietnamese, I can safely bet you not a one of them is over 5foot 4 inches tall  or barely break 100 pounds. ( apologies for not using the metric system for all of you who do and have yet to land a man on the moon).

Speaking of Vietnamese ladies using big bore handguns we have a great picture of Trần Lệ Xuân. Maybe better known to you as “Madame Nhu.” She was the sister in law to RVN’s first president, Diem and in this man’s opinion, both of them got a bad rap.  Had the left in the US not had their way and Diem was not allowed to be killed, the country would still exist to this day.   In the picture Xuân is putting on a shooting demonstration   and she was well known at the time to be an excellent shot capable of rapid and accurate shooting and pulling off some impressive trick shots.  She always used a large bore or magnum powered pistol for her shooting and would turn down offers for something less powerful. It was said she was a big fan of the .357 magnum.

There has been a lot of talk hereabout the M1903 Springfield rifle  in the last month.  Many aren’t aware of the M1922 training rifle.  Developed to  closely feel and look like the’03 but in .22long rifle. It has an interesting history that will have to wait for another day. Some very fine sporter rifles have been made with its barrel and action.   That action by the way is ultra slick.

The RIA post about the trench guns the other day reminded me  another US martial shotgun.  This one used during the Vietnam war.  The Remington 7188. The 7188  is/was a select fire combat shotgun used in small number mainly by the SEALS.   Based on the 1100 the shotgun was of course full auto.   It suffers all the usual drawbacks of using a shotgun in combat,  lack of range show to reload, limited capacity and empties too fast.   It would have been an amazing wall of lead while it lasted though. Combined with the “duck-bill” shot spreader, it would have wreaked havoc in close range jungle fighting..for a few seconds.  Which may have been all that was needed in an ambush or to break out of one.   Reliability may have been an issue in the jungle with ammo at the time.  Below some one has posed the shotgun with some ERDL uniform,  a Vietnam era shotgun shell pouch and bata type boots.  All things that would have been used by the people who carried the 7188. While the 7188 had to bow out from history, the 1100 went on to be a classic shotgun and developed into the 11-87.

With shotguns now on my brain, I have to talk about my personal favorite sporting use shotgun.   I could only be talking about the most excellent Remington Model 31.

OLYMPUS DIGITAL CAMERA

Like many  good things in this world the M31 owes its existence to John Browning.  An altered version of JMB’s Remington Model 17, the Model 31 was brought out to compete against the Winchester model 12.  It didn’t quite  match the  popularity of the Model12 and so the M870 came about and we all know how that  turned out. The Model 31  action went on to be changed slightly and used as the base for the very reliable Ithaca Model 37 and  a cheaper simplified version known  as the mossberg 500.     The model31 is in my opinion the ne plus ultra  of pump shotguns.   It is hard to describe to you how smooth and slick the action of a 31 is. It almost cycles itself.  Mine is a 16 gauge because I don’t think it gets much better than the 16 for most hunting uses.  The model 31 can be found in 12, 16 and 20. If you ever run across one, my advice is to buy it.

I don’t recall where I found this picture  below. Obviously  taken on some island in the pacific in WW2.  Two Marines pose with their newly acquired war trophy, a Japanese officer’s chest. The now dead man’s wife in a variety of pictures stuck to the lid. The level of hate both sides had for each other in the Pacific theater is probably hard for many  of current generation to understand  when thinking about how close an ally Japan has been since then.  I have often wondered if  anyone who was shown that chest at the time paused for even a second over those pictures of some Testsuo’s wife and thought maybe they were just people too.  Even monsters can love their wives.  It is fascinating to me that the same military that raped or killed everyone in china it could find had officers that had such tender pictures of their own women.    Just goes to  show the ability of many ( and you better believe it is MANY) humans to be loving and tender with some and on the other hand still  commit atrocities against other people and their loved ones as if they aren’t anything other than insects.

I have always loved the idea of the “assault kit”or the “deployment kit” when it comes to guns.  You can’t take everything you have with you as bad as you wish otherwise.  But, thanks to the unlimited modularity of the  AR15 you can take one gun and some carefully chosen accessories with an upper or two and have  the ability to tailor a rifle for several needs.

Thanks to modern tactical optic mounts, you can now have optics pre-zeroed for  an upper, or just left on an upper and swap them as needed. Then, with a choice of uppers you can have a  plan for several mission needs.  Going inside a mud hut? Put the MK18 upper on.  Maybe need to take a long range precision shot?  Put your MK12 upper on.  Or just swap optics around before you leave.  Maybe even possible to swap optics  hours or minutes before  needing it depending on circumstances.  Add to that kit a handgun or two, a suppressor and some odds and ends and you could put together a kit you could grab and travel with that would  be very versatile.   I know some like the barrel swap but this never had much appeal to me. It is a lot faster to swap uppers and changing the upper doe not require tools nor re zeroing the optic or iron sights.   No one in the real world swaps barrels on a rifle/carbine or swaps uppers in the field on a “mission” anyways so size and ability to carry a spare upper compared to a barrel is irrelevant.

In the1980s  it was still possible to buy some pretty neat stuff from other countries.  One of those I wanted but never got my hands on was the semi auto imported Valmets.

I saw and handled a couple back then but this was before I had the money to buy one. It was the M76FS.  Which is to say the folding stock model.   They are as rare as hen’s teeth now a-days and I have given up on owning one unless I win the lottery but I still think back fondly on them and how close I came.  I have said to Howard a few times  how back then we had a much larger selection of  foreign rifles, the Ar15 options were  a small fraction of what we have today.   I would give up those options from other countries gladly for the development that went into  the AR15  and the result of it today.

 

Last is a picture of my assault wheelchair.   I sometimes write reviews for movies at grindhousefilms.com and one of the guys over there  asked if I could make him a machinegun wheel chair.   I took a stab at it and produced this.   Any gun person knows it is absurd and is completely non-functional but it does look cool if I do say so myself.

 

Sorry for the lack of a normal article or review today as I said.  But I hope this was some what enjoyable for  you and a fun few minutes while you are goldbricking at work.  Hopefully things will be back to normal tomorrow.

Reproducing the Army M855 300m Carbine BZO at 25 yards

There are three most popular ways to zero the AR15s and similar 5.56 carbines.  These three are a 100 yard zero, a 50/200 zero, and the military 300m zero.  Here I am going to talk about the 300m zero.

Unfortunately most people do not have easy access to a 300m range.  Even if they did, it makes sense to start at a closer distance.  Later on I will reiterate that with a demonstration.

Why the 300m zero?  I personally wouldn’t recommend it to most people unless they are already familiar with it from time in the service.  The 300m zero has the round first cross the point of aim at 25 meters, then it raises to about 7 inches over the point of aim at about 173 yards, then it is on at 300m.  At 400 meters you are about 10 inches low.  Still easily on target.  Might be easier if I made this a chart.

Range Drop (in)
Muzzle -2.6
25 yards -0.4
25m -0.3
100 yards 4.4
200 yards 6.5
300 yards 2.5
300m 0
400 yards -9.4
500 yards -31.4

Chart made from info gathered using JBM ballistic calculator.  Figuring firing M855 from a carbine at 2970 FPS at the muzzle and a sight height of 2.6 inches over the bore.

So the real benefit to a 300m zero is that it is easier to use it to hit a man sized target at 400 and 500m just by aiming a little higher.  If you are not actually expecting to shoot those distances, something like the 100 yard or 50/200 zero would likely be the better choice.

The Army used to teach to adjust the point of impact (POI) to hit right at point of aim (POA) at 25 meters.  Some years ago they realized it was better to have the troops adjust the POI to be about 1/3 of an inch low at 25m to get closer to a correct 300m zero.  At reduced ranges small amounts of error will add up greatly at longer ranges.

So what if we are not using a 25m range, but instead the more common 25 yard range?  We can see from the chart above that that we want to be 0.4 inches low if we shoot at 25 yards.

Now to get down to the shooting.

If we are using a sight with ranging settings, we want to set it for 300 meters.

In this case I used a Matech rear sight.  I set it to the 300m setting.  I also flipped it up for the shooting.  Using a target at 25 yards, I fired a well aimed group of 3 shots.  Why 3?  It lets you use the average of the three shots to minimize error.  If you had a rifle and ammunition combination that you are extremely consistent with, you could make zeroing adjustment off a single shot.  But for stuff like this it is better to shoot groups.  The more shots the better, but 3 tends to be the minimum.

I know, from experience, that the M855 ammo I have tends to be about 2 MOA ammo.  That means at 25 yards I should be getting half inch groups.  If the group is larger than 1/2 inch, I am not doing my part.

That group is most certainly larger than 1/2 inch, so I wasn’t doing my part well there.  But it gives me something to work with.  I see that this rifle is shooting 4.5 inches low and 1.3 inches right at 25 yards.

Had I started at 100 yards, I would have been impacting 18 inches low.  I would have been completely off the target.  That is why it makes sense to start up close.

Also note my high quality custom BZO target (black Sharpie on paper).  I wanted to demonstrate you do not need a fancy target for zeroing.

On the AR15 carbine, adjustment of the front sight are about 1.75 MOA per click (1/4 rotation), and wind-age is about 3/4 MOA.

I needed to go 18 minutes up, so I decided to make an adjustment of 10 clicks.  I also needed to go about 5 minutes left, so I choose to go 6 clicks left.  (In hindsight, the math says I should have done 7)  Then I fire another group.

After firing another 3 well aimed shots I find another group that is less then perfect, but still gives me good information.  This three shot group is 1 inch low from point of aim and half an inch right.  So I need to make another adjustment.

Don’t forget, I want the impacts to be a half inch low (0.4 actually).  So I want to dial up 1/2 inch (1 click) and left 1/2 inch (3 clicks).  I make the adjustment, and fire a new group on a new clean point of aim.

There we go, zeroed in 9 shots.

Now, ideally, you tweak and confirm the zero at the full distance.

Optic of the week: Matech BUIS

The Matech sights that come from Colt have the Picatinny marking.  I have not seen this marking on these sights from other sources.

Some time back, I’m not sure when, the U.S. Military adopted the Matech Back Up Iron Sight (BUIS) as the new rear sight for the M16A4 Modular Weapon System and the M4/M4A1 MWS. That could lead one to believe that this was the best, most durable, combat ready rear sight around. Boy would you be wrong if you thought that.

Outside the military, many people have different desires for what they want out of the BUIS. Some people want a sight that locks in place and is as solid as a bank vault, those people tend to like the Troy sights. Other people want cheap, so they go with the Magpul BUS. There are a few sights that are adjustable for range with a micrometer type adjustment such as the KAC 2-600m BUIS.  There are a wide variety of features available out there, and the Matech has a pretty unique combination of them.

The main draw to the Matech is that is had a lever on the side for changing the distance setting.  This lets you quickly set the sight for settings between 200 to 600 meters, but you can not make fine adjustment for range.

An annoyance of mine is when I can not find detailed information about a product.  I know this sight was designed for use with M855 on both the M16A4 and the M4/M4A1 Carbines but I have not been able to find out what the calibration on the adjustment is.  It might have been set for the 14.5 inch barrel, or a 16 inch barrel, or the 20 inch rifle.  It might be a blended adjustment meant to be close enough for the rifle and carbine.  We just don’t know.  But in any event, it should at least keep you on a Echo Target (40″x20″) out to 600 meters.

There is a line (with out a notch to lock it in position) between the 300 and 400m marks for zeroing a M16A4 at 25m.  When zeroing a M4 at 25m leave the sight on the 300m mark.

The sight locks down, but it does not lock in the up position.  This was chosen as to allow it to move should the rifle be dropped.  Sights that lock open can be more likely to break when locked up.  Unfortunately these sights tend to wear out and stop locking in the down position.  Countless discussion and youtube videos can be found about this.

For example:

Downsides to the Matech BUIS are:

  •  It is huge, much larger than most other BUIS.
  •  If you over tighten the clamping screw and bar it will break!  Snug it up and tighten 1/4 turn past that, no more than that.
  •  You are suppose to replace the screw that is used to hold it on if it is removed from the weapon.  Most of us won’t have multiple screws laying around.
  •  It wears out!  The rear aperture latch wears out and will not stay latched down.

Now I wouldn’t say it is a terrible sight, but I do not recommend buying one.  If you already have one I wouldn’t bother to replace it unless it breaks or wears out.  Just make sure you check the distance setting on it before you shoot.