Category Archives: Weapons Accessories

Rimfire Challenge Ammo Guaranteed by ATK

ATK, a major defense and ammunition firm, likes to support the NSSF and the shooting sports. When they heard that the ongoing tightness of rimfire ammo supply was threatening Rimfire Challenge matches, they acted in the way you might expect, knowing the above, and that they’re the largest rimfire ammo manufacturer, under their CCI brand:

Adding to its Platinum-level support for the NSSF Rimfire Challenge program, ATK Sporting also will participate in the Rimfire Challenge Ammo Roundup, which will help ensure the program’s target shooters have a reliable source of ammunition.

The Rimfire Challenge Ammo Roundup will serve as a fulfillment center for match directors to purchase ammunition for events.

The company will provide 600,000 rounds of CCI rimfire ammunition to the Ammo Roundup program.

“Action rimfire sports like the NSSF Rimfire Challenge are paving the way for a whole new generation of shooters,” said Ryan Bronson, Senior Manager of Conservation and Public Policy at ATK Sporting Group. “We are happy to provide CCI ammunition to help support a program that is promoting exciting and safe trigger time for both the new shooters and folks that have been shooting for years.”

The Rimfire Challenge was the Ruger Rimfire Challenge until Ruger bowed out, claiming it had gotten to big to handle, and risking the future of the matches — sponsorless, they couldn’t survive. NSSF stepped in and the Challenge continued seamlessly.

The Rimfire Challenge combines .22 rifles and pistols, new shooters, and steel-plate targets to make appealing and fun matches. Here’s an FAQ in .pdf form. Here’s a schematic of a typical stage:

rimfire_challenge_stage_-_sample

The shooter and’s with a firearm loaded, aimed at the start steak. On audible signal here she begins to engage the plates, usually in any order, except for the stoplight. The stop plate is engaged last. (If you shoot it first, “stage over” and you’re going to do lousy on points). The scoring is based on the time to hit all the targets plus any penalties (penalties are assessed for each miss, encouraging accuracy).

The stages are relatively easy and that, and the audible clang of slug on steel, makes them rewarding for a new shooter. It would have been a shame if they ran out of ammo. Well done, ATK!

Three Reasons Not to Use the Blackhawk Serpa Holster

100 of these wound up in a landfill. Not doing that risked a lot more of the taxpayers' money.

100 of these wound up in a landfill. Not doing that risked a lot more of the taxpayers’ money.

It is our considered opinion that you should not use this product. Last SF company before retirement bought 90 or 100 of them circa 2003 (an SF company has 84 officers & men if at full strength, plus operational floats) and we discovered the same thing everybody else has: the Serpa has three serious safety-of-use problems, either of which alone would be enough to recommend retiring and destroying the holster and using anything else. Even Mexican carry.

We understand why the Serpa holster was designed. Pistol retention is a serious problem for anyone that tangles hand to hand with hostile persons. The police are more likely than armed forces to throw down mano a mano, but any soldier or Marine in ground combat can wind up in that place, the good old unsought fist fight or grapple-for-the-gun game. Many police forces, and some military units, specify a retention holster for just that reason. But there are a number of ways to design a retention holster. There are three reasons that the Serpa is the wrong way:

Safety of Use Issue #3: Stuck Pistol Syndrome

The Serpa does provide positive retention — sometimes too positive, especially if grit, sand, gravel or mung in general gets into it. If it gets into the retention release mechanism, Jesus Christ Himself isn’t getting that thing open. That’s rather a problem, because if you’re like us, you don’t generally go to unholster a gun until the situation has already gone uncomfortably nonlinear. The only thing worse than pulling your gun too soon is pulling it too late. The only thing worse than pulling it too late is attempting to pull it, and then failing to pull it at all, after signalling that you were going to. This problem by itself should be enough to disqualify this holster family.

Safety of Use Issue #2: It’s Slow

No matter how much you drill, the trigger-finger release is going to be slower than some of your other options. Worse, it’s going to be less consistent, because from time to time you may address the holstered firearm a little differently, and it doesn’t take much change in alignment to miss the flipping catch. If you miss the catch, you have to grope around, all while the clock is ticking. There are holsters that don’t make you do all this, so this problem by itself, also, should also suffice to disqualify this holster family.

Safety of Use Issue #1: Increased ND Risk

This is the biggest Serpa problem that people talk about. By using your trigger finger to disconnect the gun, and then having that finger fall on your trigger you great we increase the odds you’ll touch off a round with the pistol aligned somewhere other than at the proper target.

This video (NSFW but understandable language) shows an experienced shooter having a very typical Serpa ND. In the slo-mo at about 0:57-59 you can see exactly how it happened.

In this case, there was a combination of negative transfer of training from the more conventional 5.11 holster that this shooter used with another pistol, and the Serpa putting his index finger too close to the projectile initiator, too early in the draw sequence. Tex says he doesn’t blame the holster, he blames himself; fair enough, you can’t have an ND without human input. But his tools made the ND easier, instead of raising obstacles to an ND.

As we’ve said, every one of these issues is serious enough to warrant discarding the Serpa holster (and any holster that works like it, with an index-finger release paddle). But the increased ND risk with the Serpa is, in our opinion, the most consequential of these issues and the one that, even if you dismiss the other two, needs to sink in before you have a mishap like Tex’s.

We’re not sure even he knows how lucky he is. Mere inches from the channel that .45 slug dug in his thigh is one of the superhighways of the circulatory system, the femoral artery. A bullet in that artery would have led to his incapacitation in minutes, and ultimately, death, unless the right first aid was available extremely rapidly. He seemed to us to be alone on the range. How often have you shot, alone? It’s a calculated risk.

Doing it with a Serpa makes the calculation all wrong.

It’s not just us

We aren’t the only ones who just say no to Serpa. For example, Paul Howe wrote in 2005:

Another problem … a recent student …. exerted excessive pressure from his trigger finger to the unlock button and when drawing the weapon, drug the finger along the holster and into the trigger guard, discharging the airsoft weapon prematurely into his leg during his draw sequence.

Trigger fingers are just that, for the trigger. I think it should remain straight and have one function, to index the trigger.

Larry Vickers says:

I have banned for almost two years now Serpa style (trigger finger paddle release) holsters from my classes – several other instructors and training facilities have done the same. …. I understand many shooters use Serpa holsters on a regular basis with no issues whatsoever. However an open enrollment class environment has its own set of challenges … and a trigger finger paddle release holster is asking for trouble.

Todd Green in 2011:

At this point, pistol-training.com is going to follow the lead of other instructors such as Larry Vickers and ban the SERPA (and the various cheap knockoffs on the market) from classes beginning in 2012. I have been suggesting to students that they bring something else to classes up until now and will continue that for anyone who is already registered for a class in 2011.

And earlier that year, in reference to the Tex Grebner accident video posted above:

[T]he SERPA retention mechanism certainly lends itself to such accidents more than most other holsters. Instead of keeping your trigger finger well clear of the gun during the initial part of the drawstroke, the SERPA and its clones require you to press your trigger finger toward the trigger as you draw.

A lot more instructors say about the same thing. Travis Haley, Chris Costa, and a lot of guys you never heard of but that have seen these things cause one problem after another even on what should be a routine flat range. Rational Gun has a list of some of them, but Google will find you even more. (For example, RG has a link about the FLETC ban, but we don’t believe he mentioned the IDPA ban on the Serpa).

Yet this thing is still on the market, and people (and worse, agencies) are still buying them. Don’t Be That Guy™.

Crimson Trace’s “Foundation of Success”

crimson-trace-laserFrank Miniter writes in the normally anti-gun Forbes magazine with a remarkable business story — a profile of the way the spirit reduced to a few handwritten lists, recited with the faithfulness of a cloister’s vespers, animate a business in our industry: Crimson Trace, the maker of compact lasers and laser handgun grips, like the one on the Glock at right. A taste:

There are two handwritten lists on the sheet of notebook paper. They are written in black ink on a sheet of paper torn from a legal pad in 1994. He tells me he used to read these aloud with his business partners—mostly engineers—every morning. Small edits show it was tweaked and added to until they thought it perfect. So perfect, he says, they got so they could say the numbered lists without the piece of now crinkled and smudged paper. When that happened Lew put the lists in a frame and tacked it on the wall.

Under the title “Our Mission: What it’s going to feel like” is:

1. Our futures are financially secure
2. We all own part of everything
3. Work is fun
4. Our tools and equipment are topnotch
5. Our customers love us
6. Our building and property are impressive to say the least
7. We own other profit-making corporations
8. Our profits are at all time highs
9. Our competition cannot touch us
10. We are moving forward into the future

Lew proudly says these ten hopes and dreams aloud to me as he did every morning with his team for years.

via The 21 Rules That Built An Industry Leader.

Miniter seems to have lasered in on something that is of bedrock importance to the Wilsonville, Oregon company. While the first list describes how the founders of the company intended to wind up (and did), a second and perhaps more-important list was titled, “How do we get there?” and comprises 11 more rules. (To read it, you’re going to have to click over to Frank’s article and Read The Whole Thing™, which you know you wanna do anyway).

And here’s founder Lew Danielson’s ideas about why these rules are about people, not things; and how it influences hiring:

The rules to run a business by must deal with people, not products. This is because people create the products. When I hire someone, and I still interview everyone, I ask them about their hobbies and passion. I want to know them as a person—I figure if they made it to my office others have already vetted their resumes. When I ask someone if I can count on them and they get these misty eyes and tell me they better believe I can, well, then I know I have a loyal and passionate part of the Crimson Trace team.

Frank Miniter has far more information about the culture of Crimson Trace and the character of its people packed into his column. We’d tell you you-know-what, but we already did, right?

Science of Background-Matching Camouflage

You’ve all seen the scene from one of the Jurassic Park movies: the dinner-seeking dinosaur matches it’s background so perfectly, and blends in so perfectly, that it seems to vanish. This is a type of camouflage called background–matching (called “color resemblance” in Cott’s 1940 classic, Adaptive Coloration in Animals), and while it’s a bit speculative in dinosaurs, it’s been used for millennia by other animals — and may be used in the future by humans. We’ve seen it before in a Bond movie, too: the invisible Aston Martin.

Now see it with cube-shaped boxes on various settings around the MIT campus in Cambridge, MA.

Background Matching (“color resemblance”) is one of a very few broad methods of using color to conceal. The others are obliterative shading (countershading), disruptive coloration, and shadow elimination.

In the real world, how would such adaptive camouflage work? Andrew Owens of the MIT Computer Science and Artificial Intelligence Laboratory et al. have conducted a study (.pdf) that tested a couple thousand people on 37 iterations of algorithmically developed camouflage. The camo tried to hide a cubic virtual box, and Owens and the team used six different algorithms to try to make the box disappear from multiple angles.

The results of the test can be restated simply:

  • Algorithmic camouflage was effective at making an object hard to find. It consistently took three times as long to find the box hidden by the most effective algorithm, compared to the one with the least effective.
  • The least effective algorithm was to simply average the colors of the background into a single neutral (presumably neutral, anyway) shade.
  • The most effective used some sophisticated math called a Markov Random Field and then hid any color boundaries by requiring them to map to the actual physical boundaries of the concealed object (in the test, a cube). How does that work? Because a viewer would see the color contrast boundaries if they appeared on any one face facing him, but would only see a boundary on an edge if he could see both of the two sides that formed that edge.

We may have failed at the “restated simply” task, but we gave it a shot. For a deeper understanding, or just to have the experiment explained and the conclusions restated complexly, do Read The Whole Thing™, and check out the lab’s page about the camo project, and MIT’s press release, which talks up the pros of camouflaging HVAC and other systems hardware in otherwise historical or natural place.

We, of course, saw the military utility foremost, but then, we are knuckle-dragging widowmakers and all that.

This is enabling research that will lead in due course to adaptive camouflage. Yes, an M1A1 or Stryker or MV-22 has far more facets that Owens’s cubes, and the technology to cover those vehicles economically with conformal displays for camo purposes has yet to make it out of the lab. But this paper is an important step (not a first step, of course, because the authors build, as ever in science, on prior work) towards the translation of this capability along the RDT&E chain from concept, to science, to engineering.

Along with Owens, Professor Bill Freeman, and visiting student Alex Flint from the MIT CSAIL, the team included UVA graphic-computing expert (and inventor of Photoshop tools) Connelly Barnes, and Woods Hole Oceanographic Institute imaging & robotics researcher Hanumant Singh.

Note also that the paper has some useful stuff for those who want to understand how camouflage works and how to make it work better, in the bibliography and footnotes.

How .22 Ammo is Made

We’re suckers for the video of industrial processes, and there’s probably no process in the arms industry more automated, specialized, or cost-sensitive as the production of .22 rimfire ammunition. A crew from the Outdoor Channel spent some time at CCI in Lewiston, ID (which we didn’t know before, is across the river from Clarkston, WA) shooting video of the process from sheet brass and molten lead to a pallet of packed ammo on the loading dock.

CCI’s plant produces 16 packed pallets a day, 4 million rounds of .22LR.

And then it all goes to some guy in Ottumwa who is hoarding it all, apparently.

Some of the steps are surprisingly manual, even repetitious steps. One wonders if there’s a more automated way to do some of the manual steps they do. But they may be at an inflection point where the capital expense of further automation has such a long payback tail that it can’t be justified. Also, having a human in the loop may be a benefit if one of the things you need is flexibility. Humans are kind of “software-defined” as process steps go: they’re easily reprogrammed to do something different. The sort of analog machinery you see on this production line? Not so much.

USMC Door Gun, Afghanistan

Marine Aircraft Group- Afghanistan helps retrograde last of personnel, equipment from Sangin ValleyThis is a great photo by a Marine photographer, taken this month in the sky above our forgotten expeditionary force in Afghanistan. Official caption below; we want to say a few words about the helicopter, and the gun.

U.S. Marine Corps Lance Cpl. Matthew Ghibaudi performs a weapons check from inside a UH-1Y Huey helicopter before providing aerial assault support for ground convoys in Helmand province, Afghanistan, May 3, 2014. Ghibaudi, a crew chief, is assigned to Marine Light Attack Helicopter Squadron 369. U.S. Marine Corps photo by Sgt. Frances Johnson

We came to this via BLACKFIVE.

The Aircraft: UH-1Y ‘Venom’

The Marines are the only service still flying the 1950s-vintage H-1 Huey and 1960s-vintage H-46. But their Hueys have been rebuilt, zero-timed in fact; the airframes born as UH-1Ns were a twin engines (the Sea Services always wanted this for over-water reliability) version, unlike the Army’s old single-turboshaft H-1s (the Army equivalent being the UH-1D/H). Supposedly, 100 or so of the Y models are rebuilt Ns but the Marines have found it more economical to buy all-new airframes than to pay for Bell to disassemble, evaluate, repair and restore clapped-out N airframes, so a lot of these are all-new birds.

The UH-1Y and its sister, the AH-1Z, also have a fully articulating all-composite four-blade rotor system in place of the much simpler two-blade teetering rotor of the H-1, which inherited its rotor system, conceptually at least, from the 1940s-vintage Bell 47. The new rotor eliminates some of the low-G limitations and safety issues (look up “mast bumping”) of the original Huey rotor system. The old bird was safe within its flight envelope, mind; the new one just has a larger envelope.

In the ones based on old airframes, the airframe is gone through, of course, to ensure that it is safe for many more strenuous combat hours, and the powerplant is something a Vietnam Huey driver can only envy.

The Gun: M3M/GAU-21/A

The gun is also an update of an old classic — the John Browning .50 machine gun. The “old” door gun was the M60D, and rather than go to the M240 the Marines stepped up and used the latest version of the WWII- and Korean-vintage ANM3 aerial gun. Gun guys in all services have long known that the parts of M2 and M3 Brownings, and aerial and ground Brownings, have a high interchangeability, making almost all imaginable crossbreeds, variations, and Frankenguns real possibilities — at least, once you get into the war zone and away from the ordnance and supply clerks.

The M3  was an improvement over the Browning M2 (blasphemy!) for aerial and counter-air use. The M3 made a number of changes to allow operation at much higher rates of fire than the M2 in its aerial or ground versions; these changes included a lighter bolt and recoiling parts, much larger and oil-less buffer, relocation of the depressors from the backplate to the sideplates, and an improved, and more positive, feed mechanism that grabs the round front and rear, and can accept belts or chutes. The nominal rate of fire for the WWII ANM3 was 1200 r/min — really rocking for a closed-bolt-firing machine gun. It was available in a flexible model and (more commonly) in a fixed model, where it armed aircraft like the P/F-51 Mustang, the P/F-80 Shooting Star, and the F-86 Sabrejet.

Sole-sourced from FNH USA, the M3M, or GAU-21/A as the Navy terms it, adds a sophisticated soft-mount for the gun and numerous improvements. It replaced an M2-derived gun, the XM218 or GAU-16/A, which had evolved towards the M3 and had a mount of its own. There are many small improvements in the gun, but the big one is that it fires from an open bolt, eliminating cooking off as a potential hazard. The barrel life is claimed to be 10,000 rounds. The  M3M soft-mount also recovers the fired brass, eliminating any risk of foreign object damage, and can be fitted with night vision equipment. The spade grips are attached not to the unsprung gun, but to the buffered mount, making the gun easier to control. The improvements of the M3M seem subtle over the XM218, but they add up to a far more effective weapons system. There is also a fixed version (the M3P) for use in gun pods; these pods are commonly mounted on, among other things, SOF H-60s.

The Rocket Pod: LAU-68

The UH-1Y in the photo also is armed with LAU-68 rocket pods. Each pod carries 7 70mm FFAR (Folding Fin Aerial Rocket) unguided rockets. This rocket, originally known in Imperial units as the 2.75″ Mighty Mouse, has an interesting history of its own, as it originally was intended as an air-to-air weapon for 1950s jet interceptors (F-86D, F-89, F-94, homely and forgotten things, generally) hunting large formations of large Soviet bombers. But it long outlived the Tu-4 threat. Sine then, several generations of 70mm rocket and pod have been used by the US and its allies. A very wide range of rockets are available for helicopter and fast-mover use, and guided rockets are in the final stages of RDT&E. The LAU-68 allows ripple or single fire, but probably will need to be updated or replaced to support guided rockets, if they’re ever actually fielded. And for those occasions where you need to talk to a crowd, and fear that seven rockets may not get your message across, there’s the LAU-61, with 19 of the little beggars to show how much you care.

Let’s Make AK Mags

In this no-foolin’ great video, you see how AK-47 magazines are made, set to less-annoying-than-usual-for-YouTube music.

The crew file in to a hangar, which has industrial machinery set around its periphery (and is cleaner than we’d expect), and take their place at the machines. Here is the video; below it (although we really enjoyed watching this one on full screen) are the steps and the time hacks where you can see them, plus a few words on our impressions.

0:00 We start off in space and zoom in to Europe. Where are we going? East side of the Adriatic — inland – Bosnia! Northern Bosnia. (The manufacturer is the Matra Group, in Banja Luka, Bosnia and Herzegovina, and this is their promo video). Banja Luka is in the Republic of Srpska, a Serbian enclave whose origins lie in the troubles of the 1990s; The Matra Group shares an address with several other manufacturing businesses.

0:10 Workers in blue jackets file in. A sheet of metal stands waiting, ready to be fed into a press. Some wear blue baseball caps with a company logo, Kosmos (another of the businesses at this address, and possibly the parent of ). We see a brief shot of a digital readout scrolling.

0:27 Half a minute in, it’s mag-making time. Gloved workers carefully hand-feed a sheet of steel into a sheet-metal brake. It’s making the big, unwieldy sheets into strips that can easily be fed by one man into a machine.

0:50: On to a punch press. What’s it stamping out? Mag-half blanks. Here you see the classic curved shape of the AK mag for the first time, but it’s only a flat sheet.

1:10: The mag-half blanks are given a quick eyeball inspection and placed into a plastic tray. When the tray is full, they’ll go for further processing. It’s interesting just how manual the process is.

1:26: Another punch press (or maybe the same one with different dies?) is at once punching out and forming a bulge in parts that will clearly be mag followers. A worker has to feed a strip of steel by hand, and triggers the press with a foot pedal. The future followers are caught in a plastic tray, too. Note that everybody is wearing gloves — the edges of freshly stamped or punched parts are sharp! Despite the gloves, this plant would give an OSHA inspector the screaming willies.

1:47: Another press punches the holes or dimples in the sides of the follower that retain the magazine spring. (We skipped the process that bent the followers into a U shape). At 1:57, a worker gives the follower an eyeball inspection.

2:03: Next step, the blanks are carefully placed into a forming die, and the characteristic ribs of the AK mag are pressed into place. It looks like the locating pins for the die also help locate the magazine-half blank. Each die does two magazine halves simultaneously, side-by-side, a left and a right. Can’t tell from the video if there is one press that does two dies (four halves) at once, or two separate presses operating individually.

2:33: The worker removing the halves test-fits them together. From this angle it looks like there are two separate presses stamping the halves.

2:38: the halves are checked on a machined gage.

2:40: What’s this? A forge? We weren’t expecting that, but yes, a part of the AK mag is forged steel, it turns out. Workers remove a small, glowing steel billet from the furnace and place it, with tongs, into a forging die.

2:48: Wham! The part is forged. As a worker sprays and removes it, you can see it’s the tab on the back of the mag that engages the magazine catch. They dwell on this process for a while as it’s colorful and interesting.

3:00: A line of rough forgings have their final shape on the outside, but the mag-facing side has a lot off forging flash — all the mass of the billet that was surplus to the needs of the catch.

3:05: We see the first auto-fed machine, a Rube Goldberg contraption that is stamping out small blanks. These blanks will form the front magazine catch of the magazine, the point where it hooks in

3:20: Even this automated machine needs human tending. While the feed in is automatic, a worker stands by and winds up the scrap as it comes out of the machine.

3:38: Magazine lips are stamped out, fed, as usual in this factory, by hand.

4:08: The magazine rocker catch (front catch) is formed from the blanks we saw being punched out a 3:05.

4:15 (or so): The rear magazine catch forgings go into a press and have their forging flash sheared off.

4:38: A vertical milling machine, liberally spraying coolant, moves along a line of jigged magazine left-halves, surfacing them where they will fit into the rifle. The process is repeated for the right halves. We reckon the purpose of this is to ensure dimensional accuracy of the finished mag.

5:00: An enormous horizontal mill with a cutting disk trims a part to precise dimensions. Can’t make out what part this is under the coolant.

5:20: Vertical mill again. Can’t see what it’s doing at all, but it has an end-mill in it.

5:40: Spot-welding the magazine halves together. The jig, which provides rollers for the mag to move in relative to the single-point spot-welder, is ingenious.

 

5:42: another camera angle shows us the paired electrodes of the spot welder that welds the seam on the back of the magazine.

5:54: A single-point spot welder is used to attach: the nose cap and catch once in the frontal face of the mag (we see this operation from 4 angles); the same part, twice on each side;

6:07: Another single point welder adds the spot welds in the frontal aspect of the mag (inside the banana curve).

6:14: A special-purpose four-point spot welder welds the forged mag catch onto the rear of the mag.

6:17: Large array of bluing tanks.

6:24: freshly blued mag bodies.

6:30: We close with shots of complete mags and their components

These mags are interesting. Like Chinese magazines, but unlike most Eastern European ones, they only have two fore-and-aft reinforcing ribs at the base of the mag, and not three more ribs at the back. But unlike Chinese mags, they have the prominent back rib of all other steel AK mags.

Hat tip, Miguel, who got it from ENDO, who…

Miguel adds, à propos the mags:

Over-engineered? Yes. But they last forever. Some years back, I bought a bunch of “rescued” AK mags from the Balkan conflict, some in what appeared to be really bad shape and with dirt and even rest of vegetation inside. Some naval jelly, elbow grease and Krylon later I had a whole bunch of perfectly functioning AK mags. Only two of them were not recoverable and that was because the metal of the body was out of spec. Still I ended up with 2 spares sets of springs, followers and base plates.

We’ve had similar luck, including making a simple die to force dents out of AK mags. But it practically takes an Act of God to dent them in the first place.

UPDATE:

Because this AM post was late going up, we’re going to hold the 1100 post until 1400 to give this one some time to be seen on top.

More on Suomi Magazines

Why this post?

Max Popenker kindly corrected our error with respect to the Suomi box magazine. Because the story of Suomi magazines is interesting, we thought we’d expand on it for the assembled multitudes, rather than just type a few corrective words in the original post.

Drum Magazines

In a comprehensive history of magazines on Small Arms of the World (subscription required, and recommended), which unfortunately only takes the drum back to 1917 and not to its origins in the world of mechanical machine guns, Leszek Ehrenfeicht describes the origin of the Suomi drum:

The other variation of the true drum was a design by Oskar Alfred Östmann of the Tikkakoski Oy, manufacturer of the Aimo Johannes Lahti’s Suomi submachine gun. It has a single follower, propelled by a very strong clockwork spring; necessary to overcome the weight and friction of the 70-round content of the drum. It was less complicated than Payne’s drum, but much more susceptible to dirt; increasing the friction and raising the burden on the clockwork spring even further. Despite that, it was the most widely mass-produced submachine gun magazine of the world. What, you never heard of Mr. Östmann and his magazine? What about Comrade Shpagin and his Pepesha drum? Oh, that you know? Well, that’s the same drum. The only difference was that Finns were the first, made it in 9x19mm and paid the inventor royalties, while the Soviets copied it in 7.62x25mm and never paid a dime – but that is another story.

By “the other variation,” Ehrenfeicht means by comparison to Oscar Payne’s L and C magazines for the Thompson SMG. He classifies these as “true drums,” as compared to snail drums (essentially a single-row mag with a coiled end) and further distinguishes them from helical (Calico, Bizon) or pan (Lewis, DP) magazines by the orientation of the cartridges.

The Östmann drum was the second Suomi design, and is the most common. The first one was allowed to open, like the Thompson drum or the Chinese 75-round AK/RPK drum, to allow the cartridges to be loaded, and was more complex and less reliable than Östmann’s.

The first Suomi design was almost certainly the drum magazine shown in Aimo Lahti’s 1932 US patent, US 1,867,513. (A patent we see Max has already found and put on the world.guns.ru site’s Suomi page). The patent was also published in multiple European nations including Germany, France, Britain, Belgium and Switzerland under various numbers on behalf of the Suomi’s maker, Tikkakoski. Lahti showed diagrams for both a cylindrical feed and a spiral one in his patent, and his drum requires an internal ratchet and external wrench, or external winding ratchet also shown in the patent (this image is from the French patent, the US patent uses the same drawings separated onto two pages). Note that the Suomi itself is also patented under US 1,895,719A. (The only other US patent Lahti has is for an improved recoil-locked machine gun mechanism that apparently never saw production, unless it was in one of his AA guns: US 1,987,939).

Soumi Patent

The early drum can be seen in some photos of early Suomis. In fact, a great French history of the Suomi has photos of the drum in its rare, cylinder-feed, 40-round variant:

Suomi 40-round drum

(UPDATE: commenters A.A. and Chris Wardell have tracked the images on the French forum to the Finnish site, http://www.jaegerplatoon.net/MACHINEPISTOLS1.htm. Moreover, the text below on the M/26 that we translated from French to English seems to us to be lifted from the Jaeger Platoon site as well. We will request the site owner’s permission to use this content, but if he refuses his permission we will remove them, respecting his intellectual property).

This suggests that there never was a multi-follower, Paxton-style drum for the Suomi. (Bleg: does anybody know whence the French-speaker lifted the file? It looks like an original caption has been erased, and we’d like to give credit).

According to Frank Iannimico (same site, same login needed), the Russian PPSh submachine gun had a magazine very slightly different from the earlier, limited-production PPD-40 (the first Russian subgun to have a drum magazine. The even-rarer PPD-34 and -34/38 used curved box mags). The PPD’s original drum mag was a 73-round modification of the Suomi design, with a short “neck,” but by the time it reached production the neck was gone and the mag capacity was the final 71 rounds. The PPD and PPSh mags are identical, apart from the feed lips; one lip of the PPD’s is shorter to accommodate a protruding ejector in the receiver, and so PPD mags can be improvised from PPSh mags.

An experiment we haven’t tried is to use the Suomi drum in a PPSh or vice-versa. As the PPSh drums are a direct copy, and fed 9mm without drama in German and Finnish 9mm conversions, it’s possible, but the magazine catch appears to be in a slightly different position, requiring modification of mags, so that a truly interchangeable magazine would require a different catch.

The true origins of the “Coffin Clip”

As Max noted, the Coffin Clip originated not in Finland, but in Sweden. Ehrenfeicht again:

Another attempt at enlarging the magazine capacity was taken by Carl Schildstroem of Sweden. He designed a double compartment magazine with a single-position feed, giving, in effect, a four-row (twice the staggered row) single-position feed clip for 50 rounds. These were in fact two magazines sharing one set of magazine lips with a Schmeisser’s Cone. This magazine, called the “coffin clip” by the Finnish troops, was introduced for the Suomi SMG. It was too heavy (empty weight about 2 pounds), complicated, and failure-prone to be retained for service for any prolonged length of time. It was dropped soon after the war in favor of the wedge-shaped box. An interesting attempt at reviving the scheme was taken by the Italian company SITES for their M4 Spectre submachine gun. The M4 magazine also has a double compartment feature, but a two-position feed.

On the US Patent (2,217,848) the inventor’s name is spelled Schillstrom. It is heavy, in part because it’s built like a battleship, but our hands-on experience in firing a few hundred rounds and seeing a few thousand fired from coffin clips is that it’s actually reliable. The guns in question were very old and well-worn KP/31s that had been in use as training weapons in the US Army Special Warfare Center and School for over 30 years, and that had had some level of rebuild (as guns were refinished for the school, they got American anticorrosion finishes, in other words, parkerizing, in place of the factory bluing).

Loading the mag to capacity requires a loader or an application of physical strength using something (we used the edge of the loading table, basically a picnic table when we had more guys loading mags than we had loaders) to force the rounds down against the pressure of the followers, but not much more than an ordinary 32-round mag for a Sten or MP40 (each dual column has its own follower and spring in this design).

We did not have much luck running the coffin clips in the Swedish M45 Carl Gustav submachine gun, even though it ran flawlessly with its own 36-round wedge-section magazines. But the coffins worked fine in our sample of Suomis. Of course, our armorers had also had 30 years to fix them or cull them.

“Schmeisser’s Cone” is the term for the shape by which a dual- or multi-column box magazine squeezes the rounds into single-file for a single-position feed, because the first example was designed by Hugo Schmeisser in 1916 for an improved version of the MP. 18. It remained a toolroom experiment until after the war.

Dan Shea (same sub required) had an intermittent problem with a 50-round Suomi mag, in that he had live rounds stuck in a magazine that visually appeared clear. The Schillstrom design has three separate Schmeisser’s Cones, any one of which, or interaction between the two followers which should clear one another, might have caused Dan’s problem. (He suggests storing weapons without magazines in them, which looks less cool but is more safe).

And then there’s this oddball thing:

At first, we didn’t know what to make of it. This purported Suomi M/26 mag is for sale at GunBroker at the moment, at a very high price.

Suomi M26 mag

It is a double-feed magazine (as in the Thompson), but it’s curved like a Chauchat magazine. The claim is that it is:

[A] Finnish Suomi M/26 magazine in 7.65×22 caliber. This item shows some age and pitting but in good usuable condition. It is extremely rare.

We just don’t know enough to opine on the authenticity of this part. By 7.65 x 22, he must mean the round generally known as the 7.65 Parabellum or, in the USA, .30 Luger. The M/26 is an early, all-but-prototype Suomi.

Follow up on the Suomi M/26:

The excellent French page referenced above includes l’histoire of the Suomi, including the following:

Aimo Lathi a retravaillé son M/22…

OK, let’s do it en anglais (our translation, bearing in mind we do not do français for a living):

Aimo Lahti reworked his M.22 incorporating in it many improvements (all patented in Finland) making the submachine gun compatible with mass production.

The “konepistooliosakeyhtiö” was made by Ab Toool Oy in 100 copies, and in August 1924 the ministry of defense was interested in the submachine gun.
In February 1925, 30 examples were studied and tested by the armament commission of the MOD. The arm functioned properly, but the magazines were not interchangeable, and the barrels oxidized very rapidly.
In October 1925, the army requested 25 guns again, and 39 more in March 1936 and afterward decided to launch production of 100 examples. Most of these went to the army (60+) but some went to the Civil Guard and the border guards; conversely, very few of this series were exported (5 to Estonia). This model was called M/26.

Aimo Lahti had succeeded in his gamble: not only did his submachine gun at least as well as the Bergmann, it cost much less (2,200 finnish marks vs. 4,500).

SUOMI M/26 (7,65 Kp/26)

Caliber : 7,65 x 21 Parabellum
Length : 930mm
Barrel : 350mm
Weight : 4,18 Kg
Cyclic rate of fire : 600 cps/min
Feed : detachable box magazine, 36 cartridges
Production : around 100 examples between1925 and 1926 (in addition to test guns)

suomi M-26

The M/26 never really saw combat, as during the Second World War these guns were used by support troops behind the front.

In 1959 the 57 surviving M/26es were sold to Interarmco, something that would seem unlikely today for such a rare weapon.

Pretty neat — learned something we didn’t know previously, and found a page and a site full of new information.

Why Count Rounds?

The Army's experimenting with automated round-counting systems.

The Army’s experimenting with automated round-counting systems in the interests of better maintenance.

Well, back in SOT, the chief pistol instructor, the late Paul Poole, used to tell us “Never dry fire in a firefight!” In those days, CT work (only the British called it CQB then) was done with pistols, although we were experimenting with both the newfangled H&K MP5 and Colt’s oldfangled XM177s, a few of which were around but very beaten-up; Colt had a new version with a 14.5″ barrel that they said solved all the 177′s problems, except for the big fireball and ear-shredding report. 

We’d have gone to Hell to bring back the three heads of Cerberus for Poole, a Son Tay raider and Bob Howard’s recon-running-teammate, but it wasn’t just for his history: the guy was a dead shot, making steel E silhouettes ring with a .45 at 100 yards, and entertaining as hell, with a foghorn laugh: “Bwah-hah-hah! Never dry fire in a firefight!” when one of us was caught with his figurative pants down and his literal 1911A1 slide locked back. And his instruction was pure common sense and experience, and we all got better — a lot better — under his tutelage. 

Even if he did assess our personal pistol skills and make a little presentation in front of the guys: an M79. “Hognose, you need an area fire weapon. Bwah-hah-hah!” Ouch.

Later we found out that it was simply that somebody had to be the team grenadiers, and two of us were pulled for the honor. Poole just couldn’t resist making fun of us. (On the plus side, you get creepily good on a 79 with a couple 72-round crates a day to burn. Even if it does chew up the web of your hand).

But we did start counting rounds, at least, per mag. With the 1911, of course, it was easy. It would go bang exactly 7 times from start, and if you forgot in the stress of action how many bangs you had left, you dropped the old mag in your leg pocket (if you had time) and started counting from 7 again. What we didn’t do, though, is count rounds total. Only the snipers did that, and that was because their M14-based M21 sniper systems were a bit of a hothouse flower, sacrificing some of the M14′s robust Garand-based strength for excellent accuracy.

The snipers! Those guys were firing over our heads and next to us as we went in on training targets… one we recall with clarity was a set of wooden stairs with a door at the top and windows to its sides. In the door were two concrete cinderblocks and in each window was another. The snipers had to (and did) pop the blocks in the door as we assaulters charged up the stairs, popping the blocks in the windows with our .45s. The life of the M21 barrels was not long (the snipers did not clean them vigorously, to prevent muzzle wear; the M14 design doesn’t allow cleaning from the breach).

None of the 1911A1s had been built, as far as we knew, after 1945, and God alone knew how many rounds they’d seen. The 1911 would keep firing until a Magnafluxing at one of the periodic rebuilds showed cracks, usually in the slide. The round counts on the 1960s-vintage M16s and XM177E2s were also a mystery. Or even the newer CAR-15 carbines or MP5s… they got shot a lot.

But the idea the snipers had, to count the rounds so you knew when the rifle was about ready to go back to depot, was a good one. They actually logged them in a book (and this continued when the more-accurate and -durable M24 replaced the somewhat improvised M21 with its Leatherwood Automatic Ranging Telescope). The trouble is, of course, that logging rounds is a great deal of work. But if the whole Army could do it, we’d get a lot more information about how long small arms and their components are good for, and we could begin to schedule inspections and overhauls more intelligently. Too many inspections waste money, and some percentage of overhauls go and rebuild guns that don’t need it, while some other percentage of guns that need overhaul, based on their condition, don’t get picked up. (Army ordnance experts think that both of these numbers, the false positives and the false negatives, are about 40%)

For over 10 years the US Department of Defense’s Joint Services Small Arms Program and its constituent service ordnance departments have been trying, with limited success, to develop an automatic round counter for combat firearms. SOF elements have moved ahead of the JSSAP on this, thanks less to general SOF awesomeness, and more to SOF budgets, and they’re futzing around with fielding round counters now.

While the civilian market has round counters, they remain fiddly and unreliable, and many of them are focused on counting down the rounds in your magazine. The military frets less about that, and more about the problem of wear and tear on high cycle small arms. What they’re looking for is something that will give them a shortcut to understanding the condition of a firearm. They see this working in the way that an odometer lets you judge the point a car is at, in its factory-to-scrapyard lifecycle.

There are several ways that systems subject to wear and tear can be singled out for overhaul or rebuild:

  1. They can be selected due to calendar years of age since production or last overhaul. This is what historically has been done with most Army small arms.
  2. They can be selected “on condition.” This means that they are subject to frequent inspections, and weapons that failing inspection criterion or criteria are selected for overhaul. This is the other mechanism that sends Army small arms to the depot for rebuild.
  3. Or, lastly, they can be selected based on usage metrics. This is not done currently, because apart from sniper weapons, and for that matter, sniper weapons used by SOF mostly, few weapons have their usage recorded accurately and reliably.

Each of these approaches has problems. Calendar year replacement means that most parts you are replacing will probably still have many years of service in them. Likewise, many of the problems that degrade small arms accuracy and reliability can’t adequately be documented in an armorer’s condition inspection. Finally, usage metrics also are imperfect: evidence teaches us that not only the amount but also the intensity of use has an effect on weapons wear.

Why Counting Rounds Works for Weapon Maintenance

Let’s consider some real-world examples. The things that kill Stoner system rifles are barrel wear (which degrades first accuracy, then reliability) and metal fatigue in the locking mechanism, especially in the bolt (which is primarily a reliability threat.

The two real problem areas in rifle barrel wear are throat erosion and gas port erosion, both of which degrade accuracy and reliability. But the means the Army currently uses to detect throat erosion, the same taper gauge used to detect muzzle erosion, doesn’t work reliably at the back end of the barrel. It misses a high percentage of badly eroded chambers (well, actually, throats), “false negatives,” while identifying a rather high percentage of “false positive” chambers, that are still perfectly accurate. And outside of the depot, where the port can be examined with a borescope, there’s no way to judge gas port erosion at all.

 

Note that two of the seven lugs had failed. After the first one lets go, the overloaded remainder fail in rapid succession.

Note that two of the seven lugs have failed. After the first one lets go, the overloaded remainder fail in rapid succession, unless the broken lugs jam the rifle..

Fatigue undermines the bolt all over, but the bolts fail in two areas: the locking lugs, and at the hole for the pivot pin. Both are places where the metal is limited but stresses concentrate.

A locking lug failure (like the single-locking-lug failure common on the Beretta) may not immediately fail the weapon. That depends on where the broken chunks of lug go; but most places they might go will interfere with something. Moreover, as each lug fails, the remaining ones bear more burden, and they usually fail in an accelerating sequence as the burden of seven lugs is borne by six, five, four… the gun generally jams before you get to zero.

The next most common place for bolt failure is at the thinnest section of the bolt, where it’s drilled through to accept the pivot pin. Any asymmetry in forces here, which may result from even microscopic as symmetry of the park part, causes the forces to load up on one side or the other, and over a great deal of time, or if there’s a presence of a Nick or any other stress riser, crack begins to propagate on one side or the other. Even before the first side is completely cracked through, it’s weakened ability to bear loads increases stress on the other side, Waiting to a matching crack over there. The bolt can crack through on one side or on both, and is cracked through on one side, will quickly crack through on the other. A redesign of this area to reduce the diameter of the pivot pin, leaving more cross-sectional material in the bolt, or adding rollers to reduce friction, might increase durability here. It’s hard to judge whether it’s actually necessary, because bolt failures are relatively uncommon, and redesigning the pivot pin mechanism may introduce new failure modes.

Usually a crack at this point occurs on one side first, and can be spotted with the naked eye.

Usually a crack at this point occurs on one side first, and can be spotted with the naked eye before it propagates across the entire bolt.

The bolt seems to fail, whichever failure mode gets them, before the lugs in the barrel extension let go. Obviously bolt failures are catastrophic failures that take the weapon out of service either instantly or very rapidly (within a few more rounds); there is no fail-safe bolt failure mode. Bolt failures always occur during firing, never during non-firing weapons-handling, and therefore they have a potential to happen during combat, which is by definition a Bad Thing.

The current maintenance schedule sends small arms to the depot for analysis in large batches, commits weapons to overhaul that have years of useful life, or, even worse, sends them after they display failure in the field. Everyone knows that you have to turn in the rifles with the broken bolts illustrated here. What we don’t know is: can you catch the problem before it is catastrophic, or even visible, with round-counting?

So this is the why of round-counting (there are a few other wear modes, like to the gascheck rings, but this is the meat of it). First, we can use round-counters to identify specific weapons that have had higher usage than their rackmates, and that we would expect, ceteris paribus, to be be more needful of maintenance. Once we have an automated round-counting system in place, we can correlate round-counts with wear and failures systematically, and the data-collection potential gets interesting. A first-generation round counter is itself certainly useful, but still a rough device. All rounds are not equal, and that leaves us growth potential for improved future versions. We know from decades of experience, for example, that automatic fire wears guns of all kinds more severely than the same number of rounds fired semiautomatically, and that heavy, sustained automatic fire is very deleterious to accuracy. You may recall this post from last year wherein we noted that WWII armorers observed that .50 ANM2 aerial machine guns that had been fired in long bursts lost their accuracy even though the barrels gaged normally in all dimensions. An M4A1 is not a .50 but there may be analogies in the physics and metallurgy at work in each.

Round counters give us data points we didn’t have before, in other words.

(When we figure out where we stowed it, we’ll link the 2006 SOFIC presentation from which the images and many of the facts have been drawn).

What’s Safe Pressure in a Given Cartridge and Weapon?

Screenshot 2014-04-13 23.25.51We’re lifting this from Dan Cotterman’s Handloading column in the September/October, 1983, edition of American Handgunner magazine.

Dan, wherever he is, may well forgive us, because he in turn lifted the idea from Vern Speer (of Speer reloading fame), as he freely admits:

The late Vern Speer years ago worked out an uncomplicated and quite practical method for determining relative chamber pressures. Observing, and rightly so, that different guns produce pressures in differing amplitudes, and that test data from serious laboratories using pressure guns were often less than consistent, Spear said he’d discovered a more reliable process.

Acknowledging the fact that the cartridge case is the weakest link in the chain of components, he wrote:

“If the pressures at which these cartridge cases are fired do not exceed the elastic limit of the unsupported rim of the cartridge case, then we consider that the pressures are entirely usable, regardless of what they might be.

“We fire increased loads, increasing the charge by about a grain at a time, and check the rim diameter of the cartridge case with sensitive measuring instruments, both before and after firing. If any measurable increase in diameter of the rim of the case is noted, we consider that pressure is excessive, reduce the charge about 6 percent and list it as a maximum load in our loading table:”

Speer went on to acknowledge the value of looking for other signs of excess pressure (such as difficult extraction and flattened or cratered primers), in addition to measuring rim diameter. Note also that he cited “any measurable increase” as sufficient cause for reducing a load.

The foregoing may exist as a viable means of determining relative chamber pressures, especially for the home loader who does his work physically and financially removed from costly laboratory equipment.

That’s a sensible, simple, and practical means of setting maximum pressure when you’re developing loads. It might be a better method for using with pistols than with rifles; rifle bolts tend to provide much better case-head support than the usual pistol’s chamber does, and that case-head support might mask signs of increased pressure, especially the very subtle “any measurable increase” that Speer was looking for.

We also thought that the way Speer worded his comments suggests that he found this method not only, “safe enough to use,” but also superior to the supposed gold standard of firing in a pressure rifle. Of course, it’s not going to work with large caliber Glocks: even factory loads can bulge the cases in those!

The whole magazine, of course, is interesting, as it’s a time capsule from an era 30 years ago. In those days, American Handgunner was a bastion of revolver holdouts and 1911 fiends (in those days, we were all 1911 fiends), and covered the then-hot sport of metallic silhouette shooting.

The advertisements are our favorite part of any old magazine. In this one, they include revolver holsters and 1/3 moon clips, things that are much less popular today that they were then; aftermarket products like the Metaloy hard chrome refinish, which is still available but seems to have lost market and mind share; and products we don’t even remember knowing about at the time, like the .41 Avenger conversion kit for the 1911 from SSK Industries in Ohio. The 41 Avenger was a little bit before it’s time: the big idea was to combine the flat trajectory of the 9mm with 30% more energy. The idea’s time did come in the form of the 10 mm and the .40, but nobody remembers the .41 Avenger now. Well, we don’t. YMMV.