Category Archives: Scattered Shots

A Short History of Chrome Bores

Again this week we have a post from our friend Kevin O’Brien, owner and author of weaponsman.com.  Kevin AKA Hognose, passed away earlier this year and in a back up effort we will be running  “The Best of weaponsman”  which could be every technical article he  wrote. 

 

For some 500 years it’s been known that rifling would impart spin and therefore stabilization to a ball or bullet. Spiral grooves probably evolved from straight grooves only intended to trap powder fouling; by 1500 gunsmiths in Augsburg, Germany, were rifling their arquebuses. This gave rise to an early attempt at gun control, according to W.S. Curtis in Long Range Shooting, An Historical Perspective: 

In the early 16th Century there are references to banning grooved barrels because they were unfair. Students of the duel will recognize this problem arising three hundred years later.

Curtis, 2001. Curtis notes that why rifling was twisted is unknown, and that it may have been incompletely understood. He has quite a few interesting historical references, including one to a philosopher who explained that if you spun the ball fast enough, the demon (who dwelt in gunpowder, which was surely Satan’s own substance) couldn’t stay on and guide your ball astray. (Curtis’s work is worth beginning at the beginning, which is here).

By the mid-19th Century, the Newtonian physics of the rifled bore had been sorted out, the Minié and similar balls made rifled muskets as quick-loading as smoothbores, and the scientific method allowed engineers to test hypotheses systematically by experimentation. So smoothbores were gone for quite a while (they would return in the 20th Century in pursuit of extreme velocities, as in tank guns).

Rifling had several effects beyond greater accuracy. It did decrease muzzle velocity slightly, and it did increase waste heat in the barrel. The first of these was no big deal, and the latter was easily handled, at first, by improved metallurgy. But rifling also helps retain highly corrosive combustion by-products in the bore; and corrosion was extremely damaging to rifling. Pitted rifling itself might not have too much of an effect on accuracy (surprisingly), but the fouling that collected in the pits did. Corrosion also weakened the material of barrels, but most military barrels had such great reserves of strength that this was immaterial, also.

Fouling and pitting have been the bête noire of rifles from 1498 in Augsburg to, frankly, today. A badly pitted barrel can only be restored by relining the barrel, a job for a skilled gunsmith with, at least, first-class measuring tools and a precision lathe with a long bed. Relining has never been accepted, to the best of our knowledge, by any military worldwide.

Chrome Plating is Invented: 1911-1924

One approach has been to use corrosion-resistant materials for barrels, but that has been late in coming (late 20th Century) because it is, of course, metallurgy-dependent. Early in the 20th Century, though, American scientists and engineers developed a new technology — electroplating. George Sargent, of UNH and Cornell, worked with chromium as early as 1911, and Columbia scientists developed a commercially practical process of using electrodes to deposit chromium by 1924. Meanwhile a New Jersey professor worked with a German process.

The two groups of professors formed start-ups, the Chemical Treatment Company and the Chromium Products Corporation. At this point, chrome plating has not been applied to firearms. Electroplating had been used for guns for decades, of course, but that was nickel plating — eye-pleasing, but soft and prone to flaking, not suitable for bores, and not remotely as corrosion-resistant as chromium.

(This article is rather long, so it is continued after the #More link below. We next take up the application of this process to rifle bores).

Chrome comes to bores in the lab: 1925-32

One thing that had held chrome plating back was lack of a practical quality control method. George Dubpernell discovered a practical test almost by accident: chrome would adhere to copper, but copper would not adhere to chrome. This was later supplanted by NDT methods, but it was essential to the growth of chrome in industry.

Olin’s and Schuricht’s patent of 1932 (not 1935, a rare error in Emerson),  US Patent 1,886,218, applied chrome plating to small arms and sporting weapons’ bores. They applied for the patent in 1927, and note, as is now well known, that bores must be made slightly oversized to account for the dimensional changes from chrome deposition. They also, interestingly, saw chrome plating as a way to restore worn rifling and eroded barrels. We’re unaware of any such use being brought into practice in the intervening decades.

Meanwhile, in 1937, T.K. Vincent noted that:

Chromium plating of small arms barrels results in longer accuracy life. However, the cost of plating is excessive compared to the results obtained.

The longer accuracy life results from taming the bugbear of bore erosion. By 1942, in a thorough study of bore erosion of guns large and small (from 3″ naval guns to small arms),  Burlew noted a report by Russell that considered chrome plate a “bad” material from a bore-erosion standpoint, except “when made very adherent”; in that case it was an “excellent” material, roughly five to nine times better than ordinary plating. Chrome-plated steel barely edged out bare steel, and all beat exotic metals like Inconel and Monel; the least erosion was found in the chrome-plated barrels with the thinnest chrome plating (0.0005″), although all these tests were of a 12″ naval gun, and their applicability to small arms might not be direct or proportional.

The technology of chrome plating continued to advance, even as weapons designers struggled to bring the technology’s benefits to bear on practical small arms.

Adoption of chrome by the world’s militaries — early adopters

The Empire of Japan was the earliest nation to chrome the bores of its rifles. The Japanese had different reasons, perhaps, than other nations. In Japan, supply of high-quality steel was insufficient to wartime requirements. This is especially true after 1940, when the United States imposed sanctions on the island nation, which depended on imports for almost all resouces; and even more true as unrestricted submarine warfare, which was ordered implemented even as the Pearl Harbor strike force was recovering on their carriers, began to strangle the home islands.

Casting about for a way to work with the second-rate steels they had, the engineers at Sagami Arsenal, which was used for ammunition storage and for war production (Japan’s only 100-ton tank was built here; it was too heavy to move to the seaport for deployment) set upon a 1937 patent. They concluded that chrome-plated mild steel could substitute for some high-speed and high-carbon steels, and from 1940 that’s what Japanese engineers did. The history of a Japanese firm explains:

The Japan Science Council reported then Government to recommend the policy to apply hard chrome plating on the low grade steel as the alternative to high grade one, such as special steel or high-speed steel, under the difficult external trade conditions to get them, the invention, Patent No.131175 (1937), “the method to deposit hard and thick metal chrome plating” by Minoru Araki, the former president of Company, being as the technical foundation. It was followed by the request to establish a specialized company of hard chrome plating (industrial chrome plating) from National Headquarters of Aviation, Sagami Arsenal, and customers.

As a result, the next rifle adopted by Japan, the Type 99 Arisaka 7.7mm rifle, had a chrome-plated bore. As David Petzal writes for Field and Stream, they were “the first military barrels ever to have this feature.”

The industrial and materials-science reasoning behind Japanese chroming is missing from most US sources. Gordon Rottman (a fellow SF veteran) writes that , “the Japanese had the foresight to produce the type 99 with a chrome-plated board to prolong barrel life, ease cleaning, and protect it from tropical rust.”

In addition to the Type 99s, all of which were intended to be made with chrome-lined bores, all Type 100 submachine guns, some late Type 38 6.5mm Arisakas, and some late Type 14 “Nambu” pistols had chrome-lined bores. By late in the war, ever more serious materials shortages meant that chrome bores were one of the features deleted from late production guns (like such Type 99 features as a monopod).

The United States initially chromed only large-caliber artillery bores. From Navweaps.com:

In the 1930s, the USN started to chrome plate the bores of most guns to a depth of 0.0005 inches (0.013 mm). This was “hard chrome,” which is not the kind that you find on your father’s Oldsmobile. This plating increased barrel life by as much as 25%. The plating generally extended over the length of the rifling and shot seating. Chrome plating has also been found to reduce copper deposits.

All along, as a large body of scientific papers at DTIC reveals, US small arms developers continued to work on chrome for small arms. US engineers were aided in this by their very great extent to which chrome was being used in the automotive industry. Springfield Armory developers would have had access to many papers being produced at the same time by the SAE, and Springfield of course worked closely with the developers, themselves, of chrome industrial processes.

But chrome was not standardized for US small arms bores until after World War II — in fact, not until the mid-1950s, well after Japanese and Russian adoption of the technology. As we’ve recounted here before, the first US weapon to be manufactured new with a chrome bore was the M14 rifle. Around the same time, chrome bores were used in developing a 7.62 mm NATO conversion kit for the Browning light machine guns, and replacement barrels that were manufactured for Legacy weapons like the M1 rifle, started to be manufactured with chrome bores as well.

Because chrome bores lost some definition in the rifling, and therefore some accuracy, National Match rifles continue to be produced with standard bores. But the advantages of chrome in the field could not be overlooked.

The M16 rifle was initially produced without a chrome bore. There are two reasons for this: first, the M16 was a product of a private industry initiative, and not the usual Army development system. The disastrous fielding of the M-16, with the bare bore combined with very poor maintenance practices and some units, led to the Army adding a chrome chamber, and then finally a chrome bore to the weapon.

Another assembly of the M-16 was chromed, and this led to a lot of problems. The part in question was the entire bolt carrier group. Early on, a number of the bolts and bolt carriers failed. This turned out to be due to metallurgical problems, specifically with heat treating (that will sound familiar to anyone who has followed the M14 history), the deficiencies of which were masked by the plating, and also with hydrogen embrittlement of the steel carrier during the chroming process. The specification was changed to require the bolt to be Parkerized, except for its internal expansion chamber, and the inside of the bolt carrier key, which are still chromed (chroming only a single surface of a part does not risk hydrogen embrittlement).

Early chrome BCGs that were properly heat-treated and passed testing were allowed to remain in M16A1s by the Army, but they were not allowed to be deployed OCONUS. The reason given (in the M16 maintenance manual, TM9-1005-319-23&P) is simply to prevent glare off a chrome bolt carrier from exposing soldiers’ positions.

The USSR‘s reasons for introducing chrome plating (whether for corrosion control, ease of cleaning, or metallurgy) are unknown to us, but extensive collector interest makes it clear when the feature was added: 1950. No known 1949 SKS or AK rifles have chrome bores, some 1950 models do, and almost all 1951 and subsequent guns do. Chinese AK and SKS rifles were produced with chrome bores from their introduction in 1956. Some satellites’ bores were not chromed, notably Yugoslavia’s pre-1970s. (Yugoslavia was technically not a “satellite,” but it was a Eurasian communist country).

For practical purposes, this means that all Soviet and Chinese spec AKs will have chrome bores. In addition, gas pistons are also chromed. This greatly facilitates cleaning, and prevents corrosion in a highly corrosion-prone part of the system.

Russian small arms of larger caliber, including the 37mm tube of the RPG-7V, are also chromed.

Adoption of chrome by the world’s militaries – later adopters

Belgium, a small country that looms large in world firearms exports thanks to FN, was not an early adopter of chrome bores. The entire production of the FN-49, including all ABL, SAFN, and AFN rifles, left the FN factory with conventional steel bores. Much later, metric pattern FALs received, first, chrome chambers, and later chrome bores. What makes FN interesting enough to comment on here is their  use of chrome extended to the internal parts of their MGs and the insides of their receivers, making MAGs and Minimis very easy to clean.

US variants of these FN guns don’t have these parts chromed. The initial MAGs and Minimis purchased using using special funding vehicles by select US special operations units, had these features. In subsequent US production, the chroming was eliminated, and those parts of the M240 and M249 are Parkerized. We don’t know if this was done to save money, because the Army simply preferred the Parkerized coating, or because of the Army’s bad experience with chromed bolts on the M16A1.

Britain adopted chrome bores well after World War II, including some retrofits like the L4 Bren Gun from at least the L4A4 version to the final L4A9. As noted above, Britain’s inch-pattern FALs did not receive chrome bores.

Chrome chamber vs Chrome bore

Industrially speaking, each of these had its own pros and cons. Chroming the whole barrel was more expensive, increased demands for both manufacturing and inspection precision, required the rifling to be cut slightly oversize (to allow for the chromium deposition), and led to much greater waste. Chroming the chamber was a compromise that enhanced extraction — a sticky problem with many automatic arms — without the costs and problems associated with full-length bore chroming.

But the US experience showed that half a loaf (chroming the chamber only) didn’t get the job done. While the chamber became very resistant to corrosion, GI’s inspection of the bore often stopped with a glance in the chamber area, and if the chamber was gleaming, they’d assume the rifle was good to go — eveb as combustion byproducts and deposits ate away at the rifling.

Meanwhile, chrome bores let the manufacturers do things that were difficult or even impossible with conventional manufacturing processes. As noted above, the Japanese were able to use chromium plating to substitute for lack of chromoly steel. In the USA, Springfield Armory discovered that by slowly withdrawing the barrel, chamber first, from the chromium bath they could create a squeeze-bore effect due to the higher deposition of chrome on the parts of the barrel that were in the chrome bath longer. (Methods of altering the depth of chrome depositions produced at least two patents, 2,425,349 and 2,687,591; the second is Springfield’s process).

Chrome’s cost rises

In the 1970s, the chost of chromium suddenly went through the roof: the two greatest producers, Rhodesia and the USSR (ironically, two defunct nations, today) were locked out of the US market, the former by sanctions and the latter by international politics. (Note that around 1974 the styles of American cars began to use less chrome plate and more body-colored and black molding. This fashion was driven in part by costs).

Today, the biggest driver of rising plating costs is new environmental regulations. Chromium, like most metals, is something you really don’t want to breathe in.

Quality chrome plating is still expensive, and cheap plating produces a lot of waste. Some gun parts makers have chosen to, essentially, ignore the waste and ship products with poor (or zero!) nondestructive testing and inspection, sacrificial sample examination, or other valid QC.

Chrome plating today & tomorrow

Plating has to fight to maintain its place vis-a-vis other anticorrosion technologies, including noncorrosive metals (i.e. stainless steel) and superior steel coatings like Melonite, but it has a very strong position as an erosion fighter, particularly in barrels subject to high temperatures (think automatic fire).

Some scientists are working on electroplating as a means of additive manufacturing. Laugh if you like, but the plating industry of today was entirely based upon laboratory discoveries.

And gun engineers continue to apply new kinds of chromium treatment to bores. A recent patent application by Rheinmettal covers depositing a different thickness of chrome in the lands and the grooves of a rifled barrel.

One of the biggest changes is that a chrome-plated bore, if made with sufficient care, may be as accurate or more accurate than a bare bore. (For example, SAK manufacture M16 replacement barrels seem to outshoot many target barrels). But this may not be as big a change as you think. According to Emerson, in 1962 Springfield Armory made a small quantity of chromed National Match barrels. They discontinued the practice not because the barrels were bad, but because they were much more expensive to make than bare barrels, and they were not any better. But they were atdid fully comply with national match standards at the time.

Chrome-lined barrels are currently the standard in military small arms. This will change if and when something better comes down the pike – and not before.

References

Burlew, John S. The Erosion of Guns, Part One: Fundamentals of Ordnance Relating to Gun Erosion. Report No. A-90 Progress Report. Washington: National Defense Research Committee, 8 Sep 42. Retrieved from: http://www.dtic.mil/dtic/tr/fulltext/u2/a422462.pdf

Burlew, John S. The Erosion of Guns, Part Two: The Characteristics of Gun Erosion. Report No. A-91 Progress Report. Washington: National Defense Research Committee, 31 Oct 42. Retrieved from: http://www.dtic.mil/dtic/tr/fulltext/u2/b280242.pdf

Curtis, W.S. Long Range Shooting, An Historical Perspective. Research Press, 2001. Retrieved from: http://www.researchpress.co.uk/longrange/lrhistory.htm

Dubpernell, George. History of Chromium Plating. Products Finishing magazine, 13 Nov 12. Reprint of Plating & Surface Finishing from 1984. Retrieved from: http://www.pfonline.com/articles/history-of-chromium-plating

Emerson, Lee. M14 Rifle History and Development. Online Edition, 2007. 

GlobalSecurity.org. Sagami Depot, Japan. n.d. Retrieved from: http://www.globalsecurity.org/military/facility/sagami-depot.htm

Koka Chrome Industry Ltd., Company History. n.d. (2011 or later). Retrieved from: http://www.koka-chrome.co.jp/en/company/history.html

Olin, John, and Schuricht, Alfons. Gun barrel and process of finishing the same. Washington, 1932: US Patent No. 1,886,218. Retrieved from: http://www.google.com/patents/US1886218.

Rottman, Gordon. Japanese Army in World War II: the South Pacific and New Guinea, 1942–43. 2005: Osprey Publishing. (p. 36).

US Army, Technical Manual: Unit and Direct Support Maintenance Manual (Including Repair Parts and Special Tools List): Rifle, 5.56mm M16A2; Carbine, 5.56mm M4; Carbine, 5.56mm M4A1. Washington, DC, 9 Apr 97

Vincent, T.K. Development of Chrome Plating of Guns. Abstract only (have been unable to find the full text). Aberdeen Proving Ground: Ballistics Research Labs, 1937. Retrieved from: http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0701179

About Hognose

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

 

Accuracy Testing The Vintage 1/12 Milspec Barrel

Accuracy in modern carbines is always a popular topic on the various gun boards and news stand  slick gun rags. People want the newest barrel some company is making that promises more accuracy.  New chamber types, coatings, contours , linings and materials are all shown to us to try to win your money.

If you have read this website for a while you know I like to take a chance to convince people that their barrels on stock rack grade AR15s is already a lot better than they think and honestly more accurate that most of their users, The modern M4 carbine milspec barrel’s accuracy potential should not be ignored or tossed aside for something that costs a lot more and may not really offer any real gains.    I think I have preached this until I am blue in the face. Even stock milspec barrels are fine now a days.

But what about those from 40plus years ago?  Everyone knows those M16A1s and CAR15s weren’t all that accurate right?  We have had plenty of ‘Nam vets  tell us   Don’t forget those   cold war national guard  vets (with those old worn out A1s left over from Nam waiting to be replaced with A2s ) around to tell us how bad they were. Why , they couldn’t even qualify with them  at 25 yards with reduced range targets!!    You won’t find many people ready to argue with that.   Why would you even bother?   Those older 1/12 twist barrels won’t handle modern match rounds in the 77 or 69gr range.     But what if?..

What if that’s all you have?  Maybe you like A1 profile barrels and retro guns?  Maybe you just can’t give up your nostalgia or you just want to be different.   Or you are curious like me,  So I gave it a try.

I borrowed my friends Colt SP-1 AR15 carbine to find out.  The gun  has everything an early AR15 could be given to it by Colt.  The A1 sights, the A1 profile barrel and the 1/12 twist chrome lined Mil-spec bore.      I set the gun up on rest with bags front and read and got it as locked down as I could get it and started shooting with match quality hand loads,

Groups where shot at 50, 75 and 100 yards.  The A1 sights being a limit for me.  The older A1 front sight post shape has always been harder for me to  get the best out of it.   I used bullet weights close to the M193 load used the most during its heyday.  I selected and loaded bullets I have experience with that have always squeezed all the accuracy I could get  for shorter ranges.   Not being able to use 9 or 77 grain bullets int he 1/12 barrel I did not try for longer range accuracy testing.

The 50 and 55gr Blitzking sierra bullets are excellent, really excellent.   Those  two have always been go to bullets when loading for shots   400  yards and under when I want higher velocities, flatter trajectories and more explosive effect on targets when using rounds like the .218Bee  or .223 from a bolt action varmint rifle .   All groups are 5 round groups, You can see above how well those two weights perform.

The 55 gr Vmax from hornady is also a dependable bullet if you want an accurate bullet for varmint or target use. I used the  50 and 40gr Vmax .22cal bullets almost exclusively when I wanted a ballistic tip before sierra introduced the Blitzking.    Not to say that I think the BlitzKing is the end all be all for ballistic tip bullets,  They just shoot a bit better in some of my varmint guns.   The 40gr Vmax is still the bullet I would recommed for varmint use on small targets  in rounds that are not in the class of 22-250 or 220 swift.

Since I am on the topic, I will save my handloading component choices for a different post.

The real dependable money maker for  300 or less accuracy for milspec AR15s  is the 53 grain flat base HP matchking.  The bullet performs well in a 556 NATO chamber for a few reasons and its fairly well known.  I will go into this in a later post, but for now I will just show you the results,    The bullet is an old fav for seeing what  a milspec barrel and NATO chamber can do.   Give it a try if you handload and no one has ever told you about it.

I’m guessing that some of you may be let down that I didn’t shoot further.   I just couldn’t be sure I could use those sights well enough to shoot to the guns potential to 100 yards and beyond.  So I used the most accurate loads and fired groups at 50 and 75. I think this was a decent balance for distance and what I could see.   I did shoot some at 100 yards and the strain it put on my eyes gave me a raging headache.   When it gets like that, you can’t tell if bad groups are you, the gun or the ammo or the weather.     I rested and did the final record group of  a10 shot string.  I feel this shows what the gun could do at 100 yards or at least gives and idea of the potential it has if optics had been mounted and a better trigger added.  Neither of which I would bother to do on this classic rifle anyway.

Above is group I fired for record at 100  yards.  It is a 10 round group fired from the bench and bags at 100 yards using the 55gr blitzking.  I chose the Bltizking 55gr because it seemed to me to slightly edge out the others and I had run our of the 53gr flat base HP.  Otherwise I would have shot 100 with  the 53 grain matchking  without hesitation.

The older  SP1 Colts are still great shooters unless you  haveone some one ( or you) mistreated.  The original A1 barrels on original A1 or SP1 uppers have the same potential. They are the same Colt ( or made to colt spec by  another company for the gov at the time) made Milspec barrels.   Just because it is a 1/12 doesn’t hurt accuracy,  just accuracywith heavier bullets.  Many varmint bolt actions rifles came with 1/12 twist for 223 remington for years.  It’s about knowing  the limits of the barrels twist rate , not the quality of the barrel.    I think it is odd that a lot of AR15 users make a lot of noise about  faster twist rates in their modern guns when they never shoot anything heavier that 55gr M193 type ammo.   I suppose it’s just the thought.

If you have one of these or you have made yourself a “retro clone” with original parts, maybe you will look at it in a little different light now, or maybe some of those stories told  at the gun store round table BS sessions will seem less like wisdom and more like what they are.

Lastly. the gun ran perfectly.  It is a vintage Colt AR15  SP-1 carbine. AS you can see it has the original CAR15 metal stock which is much sought after these days and is in near mint condition.   Below is the  test carbine with Sp1 rifle.  A classic pair to be sure.

 

 

Build verses buy your first AR?

 

I saw again recently someone suggesting that a first time AR15 buyer build their own AR15 so that they would be better familiar with the parts and operation.  I think a person could learn the parts and operation of a firearm just fine without building one.

By all means build a custom AR if you want too, but I highly recommend buying a good factory built AR15 for your first one.  Having built quite a few ARs myself, and seen many more built, there are all sorts of mistakes a person can make.  I’ve seen incorrectly aligned gas blocks, gas tubes, hammer springs reversed or under the trigger pin (allowing the trigger pin to walk out.  Loose barrel nuts, loose castle nuts (allowing the stock to rotate and or the buffer retainer popping out and jamming the action), and more.  The AR15 is a pretty simple weapon, but simple does not mean that you cannot mess it up.  A factory built gun will generally be assembled correctly and you will have a warranty if there are any issues.

The best thing about the AR family of weapons is the massive amount of aftermarket parts.  It can be overwhelming, and not all of it plays nice together.  With more and more companies producing parts, they are not all interchangeable.  For example, many hand guards now do not fit correctly on various billet uppers due to these aftermarket billet uppers using different dimensions then a milspec upper.

If you buy a complete rifle from a reputable manufacture, you know the parts they choose to use will work.  If you build your own, you will need to do a little research.  Sometimes trying to just buy all the best individual components will leave you with something that won’t work together.  For example, some years back a few companies were making enhanced bolt carriers.  A guy I knew purchased the LMT enhanced bolt carrier since it was supposed to be better than a standard one.  He built a SBR with it, and found it didn’t work (The LMT carrier might not have been the only issue with it, but I’m using as an example).  The LMT enhanced bolt carrier was tuned and built for a 14.5 inch barrel or longer.  This guy just saw that there was an “upgraded” part, bought it, and never realized it wouldn’t work for him.

I could go on with more examples, but if you’re going to get an AR for serious use, or if you are not very familiar with them, it is recommended you buy a factory AR15 from a reputable company.

5 Reasons for the AK’s Legendary Reliability

 

Since the untimely passing of our friend, Kevin  AKA Weaponsman, we will be running  “the best of weaponsman.com” in his memory.

 

5 Reasons for the AK’s Legendary Reliability

AK-47The Avtomat Kalashnikova obrazets 1974g and its successors have an enviable reputation for reliability, especially under adverse conditions. There are a number of reasons for this, and we’ll go into them in some depth here. First, though, let’s say what is not a cause:

  • It’s not because of blind luck.
  • It’s not because the weapon is orders of magnitude better than its worldwide competitors. Indeed, by the end of WWII a very high standard of reliability had come to be expected, and weapons that did not meet this standard were mercilessly eliminated, like the Johnson M1941 and the Tokarev SVT.
  • Mikhail KalashikovIt’s not because Kalashnikov the man had genius that was lacking in other men. His competitors in the field, from Browning, to the Mauser-werke engineers of the 1940s to Stoner, were certainly men of genius as well. (Heck, so were Tokarev and Johnson). He’d have been the first to tell you he was just a thinking engineer.
  • It’s not because of breakthroughs. Almost every feature of the AK is recycled from somewhere else. What Kalashnikov did was synthesize them in a new way.

The Kalashnikov rifle is not, in fact, a universally superior design. Compared to its worldwide competitors (the FN SAFN and FAL, the CETME and G3, the M14 and M16 series, to name the most important), it is less accurate, less flexible/adaptable, and less ergonomic than every other. It offers less practical range than any other; and at the other extreme of range, it is the worst bayonet handle. It weighs more than some, has the heaviest magazines by far, and has an inferior weight-to-firepower ratio to most. It is inaccurate from the shoulder in full-automatic fire, yet it is designed to be fired, preferentially, on full automatic.

The strengths of the AK have overcome these deficiencies to make it incredibly common worldwide. Those strengths, compared to its competitors, include a somewhat lighter weight of ammunition, a larger standard magazine, great simplicity of operation and ease of manufacture, and that vaunted reliability, perhaps its most salient characteristic.

Design features of the AK which contribute to its reliability include:

1. Simplicity

The AK is almost as simple as a hammer. It is simple to build and manufacture (we’ll go into some specifics below). It uses no space-age materials, not even any aeronautical technology, just 19th-Century steel and iron and wood. (Much later, Kalashnikovs would have composite magazines and composite furniture. The US put composite stocks on BARs by 1944, and had them ready for the M1 and M14 in the 1950s, but an AK would not have a composite stock in its home nation for another forty years). There is no advanced machinery needed to produce an AK — indeed, one can be built (and they have been built) with hand tools and no precision measuring equipment, not even a micrometer. The rifle itself has no parts that cannot be filed, ground or machined from steel, or hammered from sheet metal, or riveted or welded from parts made this way. Most auto repair shops have the tools needed to build an AK, apart from rifling the barrel; the necessary materials are in the same shop’s scrap pile.

The AK’s operating system is simple and proven, a long-stroke gas piston system and a rotating bolt. Unlike the dainty bolt of the AR system (lifted itself from the M1941 Johnson) with its 7 precision locking lugs (and one false lug on the extractor), the AK bolt has two locking lugs, oversized, overstrong, and remarkably tolerant of undersized contact patches with the locking recesses of the trunnion. (Factory AKs have wide disparities here, especially those made by some of the more slipshod non-Russian, non-Chinese factories. The guns all seem to headspace correctly, operate normally, and fire reliably).

The AK does have one part that is a highly complex weldment: the magazine. The magazine and the feed path in general is very simple, straightforward, and repeatable, which is why the mag clearly got a lot of engineering hours. Gun designer David Findlay, who’s worked at Remington, Marlin, H&R 1871, and Smith & Wesson, says**:

Feed-system design, though, is one of the most important aspects of any weapons performance. A great deal of testing must be done to ensure good performance. Small variations and subtleties in magazine dimensions can have enormous impact on gun reliability and function.

Findlay wrote these words in explaining the engineering of the feed path of the Thompson Submachine Gun, but they’re generally applicable, and go a long way to explaining why Mikhail Kalashnikov lavished so much care on the magazine design. The fact that the receiver of the AK has received many modifications, but that the only change to the magazine is in reinforcing ribs and later magazine-body materials seems to hint he got it right.

An old engineer’s quip is that the designer’s objective is to “simplicate and add lightness.” (This has been attributed, among others, to automotive engineer Colin Chapman and aerospace engineer Burt Rutan). Mikhail Kalashnikov started off by “simplicating” most of the potential for trouble out of his design. (He didn’t make “adding lightness” a priority).

2. Environmental protection

Every designer has long known that foreign matter — mud, dust, and what have you — are the bitter enemies of reliable function in the short term, and that corrosion, rust, is the long-term destroyer of gun reliability. If you examine an AK you will see that it’s hard for foreign matter to intrude into, say, a dropped rifle. The safety, modeled loosely on that of the Remington Model 8 (a Browning design), does double duty in sealing the gap between the receiver and the nonstructural receiver cover. In operation, the charging handle, which is part of the bolt carrier, reciprocates in the open slot that the safety/selector seals shut. That seal and the lack of other large entrees into the receiver keep the interior clean.

Unlike Browning or Stoner, Kalashnikov was limited by the Soviet industrial base; he couldn’t call out exotic materials or sophisticated protective treatments, so early AKs were all steel and rust blued, an attractive finish that was weak at preventing corrosion. Some critical parts, though, notably the gas port area, the gas piston, and the bore, received hard chrome plating, and the weapon is designed in such a way that rust or pitting on other parts just does not matter in terms of reliable function or accuracy. It’s not unusual to find AKs in the field with all kinds of surface rust and pitting on their exteriors, only to find that the vitals, protected by chrome plating, have held up, and the guns still shoot within the modest (and sufficient) standards of a new AK.

3. Lack of small, dainty (and fragile) parts

A field-stripped AK contains nothing you’ll need to grope for if you drop it in tall grass (or mud, or a stream) in the dark. The pieces are big and robust, deliberately so, and this philosophy extends to the internals.

heartbreak ridge AK47 2

Nothin’ dainty about it.

The story of the development of any weapon you care to name involves interesting (and sometimes distressing) breakages. The FN, for example, was prone to firing-pin failures (the answer, which took the experts of three countries to fix, was to reduce the hardness of the part, as measured on the Rockwell C scale, and to shot-peen its surfaces: problem solved). The very first AR-10 tested by the US government had a bullet emerge from the side of the barrel in testing, not exactly a confidence-builder. (They gave up on an AL alloy barrel with a steel liner, then, which neutralized the gun’s weight advantage over the extant M14). Indeed, the AR-10 had terrible problems well into its development and production, and the Portuguese were still solving problems with it during their colonial wars in the 1970s. Many of those same problems, and a set of new ones, struck during development and production of the M16. The AK presumably had problems with these, but because the information was closely held at the time, archives have not fully opened, and most of the principals passed on without leaving technical memoirs, we know about only a few of them (for example, the failure of the first model stamped receivers, which caused a change to a machined-from-billet receiver).

The internals, though, seem to have been robust from the very beginning. Kalashnikov’s point of departure was the Garand trigger group, which itself borrowed from Browning. (Stoner would choose that same point of departure). This is part of the brilliance of the design: he wasn’t inventing for the sheer joy of inventing, but to make something that worked. That means, where he didn’t have a way of doing it better than someone else, he borrowed happily.

Borrowing aside, the Kalashnikov’s departures from Garand practice (apart from those required to render the weapon selective-fire, and to improve the Garand’s sub-optimal safety) showed a lot of interest in making things sturdier. The hammer spring, for instance, is made of two wires coiled together, giving some small redundancy; it also does double-duty in the AK as the trigger return spring.

4. Minimal use of tight tolerances

There are some parts of a gun that absolutely must fight tightly to ensure accurate, safe, and yes, reliable operation. On the AK, almost all of those are permanently assembled at the factory (the barrel into the trunnion, for example). The trigger mechanism is designed with a lot of slop and play in it, which is why AKs have that typically very long, smooth trigger pull with a surprise let-off (SKSes are similar), but it isn’t that way to manage the trigger pull: it’s there so the mechanism will be positive and safe the first time and the 1,000,000th time.

The only moving parts with truly tight tolerances are the fit of the bolt lugs into the trunnion, which affects headspace. For safety and accuracy headspace has to be right on. But the non-bearing surfaces in the trunnion are opened up enough that dust and dirt has somewhere to pack into, other than interfere with the tight fight of bolt to trunnion. John Garand considered the wise use of tolerances key to the legendary reliability of the M1*. Like the AK, its only critical tolerances in the operating mechanism come from the interface of the lugs of the rotating bolt with the mating recesses of the receiver.

5. Use of very loose tolerances everywhere else

Garand deliberately eschewed the use of a bolt carrier in place of an operating rod. He considered the competing bolt carrier and tipping bolt design (as used in Tokarev, Simonov and FN rifles) more troublesome both in production and in service because they had more critical tolerances. While the AK uses a bolt carrier, its fit to the bolt and receiver is if anything even less critical and looser than Garand’s op-rod.

What Rayle (and Garand) thought of as an innate flaw in bolt-carrier vs, op-rod systems, the need for precision tolerances both on the locking/headspacing feature of the bolt and its receiver, and also on the interface of the bolt with the bolt carrier, turns out to be an innate flaw in the Browning (Tokarev, Simonov, Saive, Vervier, etc). tipping bolt. The AK’s bolt can interface with its carrier just as loosely as the M1s does with its operating rod, with no harm to the functioning of the rifle.

This is not to say that nothing on the AK is manufactured with precision. (That would be the STEN). The beauty of the AK, from an engineering design viewpoint, is that nothing is manufactured with unnecessary precision.

To Sum Up

aklgcolcopyThese things, taken together, suggest that the AK is narrowcast at its original role as a submachine gun replacement for the semi-literate peasant conscript army of a nation lacking depth in precision manufacturing. It was the perfect gun for the Red Army in World War II, even if it came a little too late. It was also, therefore, the perfect gun for the continuation Soviet Army.

Unlike the service rifles of the USA or Germany, or the first-generation battle rifles of the West in the 1950s, the AK was manufactured without an excess of precision which limited its adaptability as, say, a sniper rifle. (The AK’s then-unique use of an intermediate cartridge also did this). But it suited Soviet doctrine of mass attacks and mass fires well. Unlike the NATO rifleman, the Soviet soldier, although instructed in semiautomatic fire on ranges, was also extensively drilled in live-fire obstacle courses, and was expected to run them firing on full-automatic, from the hip. He was the heir of the submachine-gun battalions of the Battle of Berlin, and planned to fight the same way, as mechanized infantry guarding the flanks and securing the obstacle-ridden forests and towns to enable the great tank attack. Hence, the first click off safety on an AK is full-auto, contrary to every successful NATO selective-fire rifle.

The same adaptations, design decisions, and production practicality that made the AK a perfect replacement for Ivan’s retired PPSh submachine guns, made the AK a perfect weapon for terrorist groups, “national liberation” movements, and under-resourced armies of newly free colonies worldwide.

Like the Mauser before it, the AK is a universal gun. And like the Mauser, the AK will be with us until something better supplants it. And “better,” in this case, will be defined by history and by nations, not necessarily by gun experts.

 

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* John Garand’s comments come from Rayle, Roy E. Random Shots: Episodes in the Life of a Weapons Designer. 

** Findlay, David S. Firearm Anatomy: Book I: The Thompson M1A1 Submachine Gun. p. 76. San Bernardino, CA, 2013: Findlay, David S.

This entry was posted in Foreign and Enemy Weapons, GunTech, Industry, Rifles and Carbines on by .

About Hognose

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

The site owner is a former Special Forces weapons man (MOS 18B, before the 18 series, 11B with Skill Qualification Indicator of S), and you can expect any guest columnists to be similarly qualified.

Our focus is on weapons: their history, effects and employment. This is not your go-to place for gun laws or gun politics; other people have that covered.

Assorted chatter.

I’m never really sure what to say on occasions like Memorial Day.  I think SoldierSystems summed up my thoughts a little more elegantly then I could have said.

I’m happy and upset with the Razer brand.  I’ve long been a fan of Razer mice, so when I was looking for a wireless headset I ended up getting a Razer Man-o-War.  Really awesome headset.  Some time ago I broke one of the pads on it, so I contacted them and asked if I could buy a replacement pads.  They said they didn’t have spare parts, but they would be willing to take my broken headset back, give me full store credit for it, and free shipping on my next order.  I was surprised, and took them up on the offer.  Irritation finally set in when after receiving back my old headset they dragged their feet a couple of weeks before giving me that store credit.  But now all is well and I have a replacement on its way.  I thank Razer for replacing my broken headset, I just wish they would have done it faster, or better yet just sent me a replacement pad.  In the end, for about $12, I have a brand new headset on its way to me.

Gulf Coast Armory

I swung by Gulf Coast Armory to drop some stuff off for Cerakote.  When I was looking at some of the work Jeremy has recently done, this caught my eye.  A cross between the Superman logo and the Autism Society puzzle pieces.  I really love how that piece looks.

Gunner Wade on Silencers

Where the hell was this guy when I was in?

I still run into many people who believe that silencers drastically degrade accuracy and velocity.  Unfortunately this myth is still common in many popular video games, and all too many people believe that to be a fact.  A good deal of the pro gun youth only know firearm info from the games they have played.

It is true that some of the early pistol and submachine gun silencers that relied on wipes, mesh, or large internal volume to keep .22 and 9mm rounds subsonic did reduce velocity and accuracy/precision.  Modern designs don’t do that, and can actually give a small increase in velocity.  I’ve seen some rifles shoot tighter groups when shot suppressed.

Kinetic Concepts Tactical Rhodesian Kydex Holsters

The fellows over at KCT have made up some their excellent Element I  IWB kydex holsters done in Rhodesian camo for the guys at Rhodesian Arms.com.     After seeing some other pictures on KCT’s instagram account I was impressed. I have always loved this cam pattern,

If you like it, get in touch with KCT as they have said they are willing to work something out with you so you too can have one of these special run holsters.

 

GM94 Grenade Launcher

I was pointed to this youtube video about the Russian GM94 43mm grenade launcher.

Now, I don’t know Russian, so I have no clue what they are saying.  My first impression is that it looks like a handy launcher.  Our M203s and M320s are single shots, and the M32 6 shot launcher is somewhat awkward.  This seems like it would be easier to pack and deploy than the M32.  Being able to fire 3 rounds quickly would certainly be handy.

I doubt very many of us have any experience deploying thermobaric grenades, but I certainly would love too.  They are suppose to be more reliable and effective then fragmentation grenades for incapacitating or kill in their effective radius.  We have been fielding thermobaric rounds in our SMAWs, and even have one for the 40mm launchers (XM1060).

In the end, this video above is worth the watch just for its cutting edge computer graphics.

The Best of “Weaponsman” Part 1 (M16A1 Maintenance Survey in Vietnam)

As we reported last week and as everyone familiar with this website knows, our friend Kevin O’Brien, AKA “Hognose”, passed away. Kevin was a good friend of looserounds and  we often shared info back and forth for a variety of gun related topics.    Not 100 percent  sure that weaponsman.com has will be available in the coming years I will be running a weekly ( or maybe more or less often) “best of post” of some of Kevin’s best stuff  from his website to save  it for all and as a tribute to our friend.

 

M16A1 Maintenance Survey in Vietnam

By Kevin O’Brien ” Hognose”

We’re looking at a declassified report from the US Army Weapons Command in 1968. The report is available to subscribers to Small Arms of the World in their archives. And we came across the following little gem, which we’ve already served with several Vietnam-SF buds. Emphasis ours:

The first USAWECOM survey team stayed in Vietnam from 21 October1965 until 2 December 1966. (4) While the primary purpose of the team (5) was to provide maintenance instruction to a nucleus of officers and men from each brigade, who would then teach their own units, direct support organizations wece also instructed.

The team taught maintenance in every major USARV unit except the 1st Air Cavalry Division. (6) Students brought their own weapons, magazines, ammunition, cleaning materials, and accessories to class. A detailed inspection of each student’s equipment revealed that with the exception of the weapons of the 1st Brigade, 101st Airborne Division, the 173d Airborne Brigade, and the 5th Special Forces, all the weapons were poorly maintained.

The footnotes (4) and (5) refer to the team’s report and describe the makeup of the team — led by an ordnance LTC with four experts from USAWECOM and three from Colt. Note 6 explains why the Cav wasn’t trained — they said they were having no trrouble with the M16A1, and asked only for instructors to work with its divisional maint battalion small-arms shop.

So what was jacked up about the GIs’ guns?

The most common faults observed were:

  1. Excessive oil on the weapon
  2. Carbon buildup in the chamber, bolt, and bolt carrier group
  3. Overloading of magazines with 21 rounds of ammunition
  4. Oil and grit inside magazines (frequently accompanied by lubricated ammunition); and
  5. Failure to replace worn or broken extractors and extractor springs.

Other deficiencies noted frequently were shortages of technical manuals, cleaning equipment, and repair parts, and a general lack of knowledge of the M16 rifle among officers and noncommissioned officers.

At first it may seem strange that soldiers were unfamiliar with their weapons, but you have to remember how this report fits into American small arms history. The M16A1 was a standard — in Vietnam, only. The rest of the Army still soldiered on with the M14, and an awful lot of people in Army Ordnance still had their noses out of joint that Westmoreland had ordered a lot of weapons that were Not Invented Here (the M14, like the M1 before it, was developed in-house by the Army). Some of them wanted the M16 to go away. Others wanted it to fail. Still others were captivated by the small-caliber, high-velocity concept and the M16’s brilliant ergonomics, and determined to help make it work. And many were of a type with Army men of all nations and all times: given a mission, intent on carrying it out.

We thought it was interesting that three airborne units (the 101st was still nominally Airborne at this time, although it would only have the name as n honorific by the time it left Vietnam) had few worries with their M16s, although it seems like the 1st Cav didn’t either. So why were the airborne units squared away, when most of the legs weren’t? Turns out that it wasn’t due to the higher quality of troops in the supposedly all-volunteer paratroop units, but had a more mundane explanation:

The 1st Brigade, 101st Airborne Division, the 173d Airborne Brigade, and the 5th Special Forces were the only units surveyed that had received training with the M16 for a significant period of time prior to deployment to Vietnam. Men in other units had been given training in marksmanship but little or no instruction in care and cleaning of the rifle.

On a follow-up visit, intended to cover maintenance of the very maintenance-intensive XM148 grenade launcher, a subsequent team discovered that many of the M16s turned in for maintenance (which might not be typical of all M16s in the field; a working weapon doesn’t get turned in for maintenance) had pitting in the chamber. They did the math and came up with a statistical prediction that 10% of all 16s in Vietnam would need a replacement barrel every three months. That correlated nicely with field complaints of extraction and ejection problems. One answer was to add chrome plating to the chamber (later, the whole bore) of all M16A1 rifles, and this report seems to be where that suggestion was first committed to official writing. This suggestion was not exactly rocket surgery: at the time, the Russians had been doing it for 20 years.

The chrome chamber weapons have “MP C” or “C MP C” markings on their barrels. The later Vietnam-era chrome bore weapons are marked “C MP B.” After the war, the marking changed to “C MP CHROME BORE” and that’s what most of the small supply of surplus M16 barrels say. The bore chroming is not a sign of a particular model of M16, it’s simply a running change, one of many hundrendrds

A lot more interesting stuff in this report. There is a CYA aspect to some of it, for sure, but it’s a window into a problem (M16 Jamming, circa 1966) of which much has been written, usually without reference to primary sources like this.

About Hognose

Kevin  O’Brien  was a Former Special Forces 11B2S, later 18B, weapons man. (Also served in intelligence and operations jobs in SF).