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June 23, 2013 8:08 PM   Subscribe

AMMO - oddly beautiful cross section photos of ammunition by Sabine Pearlman, taken in a WWII bunker. The io9 write-up has Redditor identification of the cartridges.
posted by Artw (59 comments total) 14 users marked this as a favorite

 
Terrifying to think that each of those serene, mechanical cross-sections was engineered, from design to manufacture to use, to kill as efficiently as possible.
posted by maryr at 8:14 PM on June 23, 2013 [3 favorites]


They all give me the chills, particularly the ones with the fletchettes and ball bearings.
posted by arcticseal at 8:17 PM on June 23, 2013 [1 favorite]


ball bearings

Those are "non lethal"... Yeah, not sure I buy that either.
posted by Artw at 8:19 PM on June 23, 2013


Wound cross-sections.

And, FWIW, they probably are "less lethal" - sure, they'll cause some pretty nasty stellate superficial damage, but far less likely to penetrate deep enough to hit anything you care about (arteries, central nervous system, liver...).
posted by Ryvar at 8:30 PM on June 23, 2013


That's incredible -- I had no idea that's what was inside. Nice post!
posted by spiderskull at 9:37 PM on June 23, 2013


How does she get the cross-sections? Aren't they filled with stuff that goes boom?
posted by kenko at 10:00 PM on June 23, 2013


Man's endless capacity to find new and innovative ways to end the lives of their fellow man is fascinating and terrifying. These are beautiful, but I'm not happy to like them so much.
posted by nevercalm at 10:38 PM on June 23, 2013 [1 favorite]


kenko: I don't know how they got these cross sections, but my dad worked on a project which needed gold components. Failed components were embedded in resin blocks and rubbed against abrasive plates until worn down (in retrospect I wonder if it was bandsaw then polish against a plate). Cross-sections made that way are kinda beautiful.
posted by Leon at 11:11 PM on June 23, 2013 [1 favorite]


The "ball bearings" are, I guess, shrapnel shells. Shrapnel, which is often used to denote shell fragments or other debris, is a thing.
posted by thelonius at 11:32 PM on June 23, 2013 [1 favorite]


This is what came up in a Google search for ""cobra high safety ammunition". It's like a photo of Green Arrow's ammo dump.
posted by Joe in Australia at 11:47 PM on June 23, 2013 [1 favorite]


My workplace was a WWII ordnance plant before the war dept. sold it to my company in 1946. I have to wonder if anything in these photos came from here...and sometimes while I sit at my desk late at night, I wonder how many people died as a result of this place.
posted by TrialByMedia at 12:16 AM on June 24, 2013


The "ball bearings" are, I guess, shrapnel shells. Shrapnel, which is often used to denote shell fragments or other debris, is a thing.
posted by thelonius at 2:32 AM on June 24 [+] [!]

No disagreement, though it's worth noting that that's a fairly tiny round - 9mm. Those balls are each only two or three millimetres in diameter. Still nothing I'd want to be remotely close to, mind, but not as catastrophic as they'd appear. The difficulty in assessing the scale of the photos makes them look a lot larger than they actually are - as opposed to that 7.62mm salvo squeezebore in picture 5, which looks comparatively similar but is absolutely terrifying.
posted by ZaphodB at 12:23 AM on June 24, 2013 [1 favorite]


The fletchettes are depleted uranium in a sabot to penetrate body armor I think. I think the blue one is a Teflon "cop killer" right?
posted by Ad hominem at 1:06 AM on June 24, 2013


Aw man, I am totally wrong. I suck at this game.
posted by Ad hominem at 1:11 AM on June 24, 2013


I'd really like to know how the bullets were split so cleanly. I wouldn't be too keen on taking a bandsaw to any of these, but maybe I'm overly sensitive about explosives.
posted by startled at 1:29 AM on June 24, 2013


I think the blue one is a Teflon "cop killer" right?

According to the io9 article, it's a plastic short-range training tracer.
posted by Pyrogenesis at 1:49 AM on June 24, 2013


I'd really like to know how the bullets were split so cleanly. I wouldn't be too keen on taking a bandsaw to any of these, but maybe I'm overly sensitive about explosives.

I assume the bullet is pulled out of the casing, the charge poured out, then they can be cut and reassembled, however that doesn't explain the primer cap. I have no idea how you would safely cut a primer cap. I notice they don't seem sealed - perhaps the path by which the primer ignites the charge can be used to remove the primer?
posted by anonymisc at 2:03 AM on June 24, 2013


Flechettes are actually terrible at penetrating modern armour despite their thin cross section and high speed, at least at the small arms level (the APFSDSDU rounds fired from modern tank guns are extremely good at this however). Lots of research in the 1960s was done around flechette ammo and again in the 80s when Steyr were using them as the basis of their entry into the Advanced Infantry Combat Weapon (AICW) project.

In the 60s the problem was flechettes were crap at going through the jungle foliage and Vietnam was the war of the day. Come the 80s the conclusion was that they were unstable at range and inaccurate and further, didn't possess sufficient capability to actually incapacitate the target. This didn't stop them being immensely popular in cyberpunk literature of the time (damn you Gibson!).

Teflon coated rounds have been used as a police issue round to penetrate cover without spalling, tumbling or going off in weird directions. This was an issue for police snipers (some of you may recall the hostage crisis about 15 years ago where a police sniper shot at a suspect through a glass window from less than 100 yds and the glass sent the bullet off course injuring a hostage).

These sorts of bullets are now known as "barrier blind" rounds and are designed slightly differently*1. The whole Teflon-coated = Armour Piercing is bullpoop. You make stuff AP by making it heavy, fast and pointy. I can't look at work thanks to some over-protective crap that makes anything with the word "gun" inaccessible but is there perchance a duplex or triplex*2 round in there? Also be interested if there is some Gyrojet ammo in there. That stuff if also awesome 60s level crazy.

*1 see the M855A1 SOST cartridge here as an example.
*2 a single cartridge with two or three individual projectiles.
posted by longbaugh at 2:21 AM on June 24, 2013 [4 favorites]


The whole Teflon-coated = Armour Piercing is bullpoop.

Teflon coating on armour-piercing ammunition is to protect the barrel from the hardened metal of the bullet which would otherwise cause much more wear than a normal lead bullet.
posted by atrazine at 2:49 AM on June 24, 2013 [2 favorites]


I refer to the concept of teflon coating a Ball round to make it into AP and the whole "cop-killer" bullpoop of the 80s (including Lethal Weapon). Wikipedia's article on the topic is surprisingly accurate. Whether specifically AP ammo is coated in a protective layer is a different matter and whilst the wiki article on AP ammo mentions it I wouldn't take it too seriously.

In my reading around the subject it is more common for the Teflon or molybdenum to have been applied to allow better penetration of cover as a solid projectile (i.e. the barrier blindness I mentioned before) rather than to reduce barrel wear which is going to be statistically neglible in military firearms (i.e. the only folk using AP rounds) compared to things like tracer rounds. It otherwise reeks of firearms-related woo to me.
posted by longbaugh at 3:19 AM on June 24, 2013 [1 favorite]


Those are beautiful pictures, made even more intriguing by the lethality of the subject. It's pretty impressive how much design and engineering goes into some of these.
posted by Thorzdad at 4:29 AM on June 24, 2013


This reminds me of one of the most incredible sculptural objects I ever saw. It was on exhibit at the Yasukuni Shrine in Tokyo. The museum is controversial because it is one big justification for Japanese militarism in WWII. It sickened me, as it does many Japanese people.

The museum has a large display of personal objects and uniforms of soldiers. Amidst them was an ammo clip. You've seen the kind, a row of maybe 8 bullets attached with a clip at the end. But this clip was hit by a bullet. It penetrated the casing of the top bullet, and went down the row of cartridges, making a hole in each one, and making them bulge slightly, then the bullet stopped about 3/4 of the way down the clip. One bullet hit the other bullets and destroyed them. I thought it was a perfect symbol of militarism, they want it to seem like just the weapons fighting against other weapons, and ignores the messy human casualties that sully the conceptual purity of the battle.

I would have taken a pic but no photography allowed. I've considered going back specifically to get permission to photograph it.
posted by charlie don't surf at 4:33 AM on June 24, 2013 [2 favorites]


How does she get the cross-sections? Aren't they filled with stuff that goes boom?

I would guess something like a water jet cutter is used. I don't know enough about the process (or ammunition manufacture) to say if they can stop things from shifting during the cut.
posted by cardboard at 5:01 AM on June 24, 2013


You make stuff AP by making it heavy, fast and pointy.

Penetration is (on the projectile end) governed by Kinetic Energy / Cross-section, or: 1/2 m v^2 / pi * r^2, where r is the radius of the bullet when viewed along the flight axis. That's why anti-tank rounds (Armor-Piercing Fin-Stabilized Discarding Sabot, or APFSDS) look like a thin arrow after the sabot has been discarded, and usually have muzzle velocities >1500m/s.

My point is: velocity's effect on bullet penetration is exponential, which was among the reasons both NATO and Warsaw Pact nations switched to smaller, higher-velocity rounds like 5.56x45mm and 5.45x39mm (there are additional benefits such as lower recoil, flatter trajectory, higher carrying capacity per pound).

The complication is that velocity's effect on momentum is strictly linear: m * v, and air turbulence increasingly becomes a factor at higher velocities so there's a definite trade-off there. Part of the response on the NATO side was to increase bullet spin by upping the ratio on barrel rifling, which lead to an interesting side effect: 5.56mm bullets with thin metal jackets impacting at under 100m have a tendency to shatter due to torsion/shearing forces.

Which basically meant violating the Geneva Conventions against fragmenting ammunition in practice, while allowing the Western powers to honestly claim not to have designed their bullets for that purpose.
posted by Ryvar at 5:49 AM on June 24, 2013


Which basically meant violating the Geneva Conventions against fragmenting ammunition in practice

They were the Hague Conventions, in 1899. And in 1907, which banned weapons that caused "unnecessary suffering."
posted by the man of twists and turns at 5:53 AM on June 24, 2013 [2 favorites]


There are a couple of big boards hung up at the PT Boat Museum at Battleship Cove. They show many different kinds of shells for familiarization, from itty-pitty pistol rounds up to the banana-sized ones fired from a PT boat's 30mm deck gun. In an abstract way they are pretty, what with all the colored paint stripes and different colored fillers. I have pictures somewhere that I took for a friend's book.

These displays are WWII-vintage, so I doubt they were made with anything as fancy as a water jet; my hunch is that the fillers are fake. *shrug* Then again, given some of the ahem shortcuts in WWII manufacturing, who can be sure?
posted by wenestvedt at 6:02 AM on June 24, 2013


These are pretty much the same as what you will find in any shooting magazine.

The "ball bearings" are, I guess, shrapnel shells.

They are just common "less lethal" handgun rounds loaded with shot. They are used in for tight quarters home defense or to scare off large animals.

I'd really like to know how the bullets were split so cleanly. I wouldn't be too keen on taking a bandsaw to any of these, but maybe I'm overly sensitive about explosives.

The only explosives in ammuniton is in the primer cap. The powder is a propellant, not an explosive. The powder will only burn if you give it a source of ignition and when it does it's pretty unspectacular.
posted by The 10th Regiment of Foot at 6:39 AM on June 24, 2013


Penetration is (on the projectile end) governed by Kinetic Energy / Cross-section, or: 1/2 m v^2 / pi * r^2, where r is the radius of the bullet when viewed along the flight axis. That's why anti-tank rounds (Armor-Piercing Fin-Stabilized Discarding Sabot, or APFSDS) look like a thin arrow after the sabot has been discarded, and usually have muzzle velocities >1500m/s.

Yeah... I didn't bother with the equations since the summary heavy, fast and pointy is enough for most folk.

...5.56mm bullets with thin metal jackets impacting at under 100m have a tendency to shatter due to torsion/shearing forces.

I wrote a really boring answer to this covering barrel twist ratios and bullet weight and stuff about the Army's recently failed Individual Carbine trials but then remembered this isn't AR15.com and that shit is really boring to most people. In summary - this isn't always the case for a host of very tedious reasons that gun bunnies will be happy to bore you to death with. It's also cost the Pentagon millions of dollars for no discernable improvement thus far.
posted by longbaugh at 6:50 AM on June 24, 2013 [3 favorites]


longbaugh: dude, this is metafilter. that kind of shit just gets favorited or ignored. who knows, we might learn something.
posted by lodurr at 7:14 AM on June 24, 2013 [1 favorite]


Honestly, longbaugh, I'd have been interested in that post. The best part of Metafilter is when people who are informed on a topic pitch in because that way the rest of us with only amateur levels of knowledge can benefit from their insight. Holding back "because this isn't AR15.com" serves no purpose other than keeping discussion comfortably insubstantial, and Facebook's got that covered, y'know?

Point is, I'm happy to admit that on this topic I'm nothing more than random Internet dude with Wikipedia and some morbid interest. Sorry if it read like an e-Penis comment, was not my intent.
posted by Ryvar at 7:15 AM on June 24, 2013 [2 favorites]



My workplace was a WWII ordnance plant before the war dept. sold it to my company in 1946. I have to wonder if anything in these photos came from here...and sometimes while I sit at my desk late at night, I wonder how many people died as a result of this place.

Or, how many were saved by the bullets hitting the aggressor and thus ending the conflict. Perspective is not only for pictures.
posted by HyperBlue at 7:43 AM on June 24, 2013 [2 favorites]


I am knocking off work now but I've hashed out about ten paragraphs of stuff that I have emailed to myself and will try my best to post tonight.
posted by longbaugh at 8:02 AM on June 24, 2013


These are great.
posted by nathancaswell at 9:17 AM on June 24, 2013


So, like, the only thing WWII was the bunker. The ammo was apparently of modern construction and conversion, which seems kind of weird given the photos could have been shot on the kitchen table as much as the locale is evident in the photographs. There's a lot of e-ink on this display (much of it apparently wrong) but some cite the site as part of the artistic process but again, really? If the location had an impact on the artist, its lost in a sea of nearly identical compositions. Nice marketing hook, though.
posted by Ogre Lawless at 11:33 AM on June 24, 2013


The ammo was apparently of modern construction and conversion, which seems kind of weird given the photos could have been shot on the kitchen table as much as the locale is evident in the photographs.

That last one in your link doesn't seem right. It looks to me like some sort of frangible, sintered "slug" with a plastic ball that's similar to the .38 glaser. Sort of like a varmint grenade for a lower velocity (warning video is graphic), the ball would protect initial penetration but would allow the bullet to immediately fragment.
posted by The 10th Regiment of Foot at 11:47 AM on June 24, 2013


12 ga - 3" Uranium Drone Load - 1 3/8 oz - Tacnition - 5 Rounds

Yes, it's a joke.
posted by homunculus at 7:16 PM on June 24, 2013


Company Sells Pork-Laced Bullets Designed To Send Muslims To Hell

This, it seems, is not a joke.
posted by homunculus at 7:25 PM on June 24, 2013


Pork-laced bullets.

Also, I'm pretty sure you can't send a muslim to hell by shooting him with a bullet covered in bacon fat. Allah would be a pretty crappy god if he let that happen.
posted by lodurr at 5:49 AM on June 25, 2013


I wanted to apologise to Ryvar first. I lashed out where it wasn’t appropriate for me to do so – I clearly misread his intent to share and inform. Sorry mate. I was a dick and I hope you can forgive me :)

So anyway, I ended up writing stuff through until 2am before going to sleep and in my half-zonked state committed the cardinal sin. THOU SHALT NOT FORGET TO SAVE THY WORK. As a result I've had to cobble the following together, mostly from memory. I’ll happily accept any corrections from those brighter or better informed than I.

The wounding capability of the 5.56mm NATO round is caused by the yawing of the bullet, an effect of the shape of the projectile, the way in which it spins through the air and it’s velocity. I'll cover each of these below. Just to warn you, it's going to be really long and cover a host of historical, political and technical issues.

Bullet design
I will focus on the 5.56x45mm NATO here. The 5.56mm is the calibre or diameter of the bullet and the 45mm is the case length. The bullet is quite long in comparison to it's diameter with an approximate l/w ratio of 5:1. In comparison, pistol calibre rounds often have l/w ratios of 2:1. The long cross section of the round means that it can be affected significantly by winds, which is why the round must be stabilised to avoid impacting on accuracy at range. Pistol rounds are not only shorter but also are generally heavier and slower and thus less likely to be affected by wind.

The original military 5.56mm round was designated the M193 and used a 55grain (~3.5grams) bullet. This was based on the .223 Remington, a lightweight round used for hunting small to medium varmints such as coyote. In the 1970s NATO decided on some small changes to the 5.56mm due to changes in requirements. A newly designed round from Fabrique Nationale (FN) was adopted, the SS109, designated the M855 in US service. This uses a 62gr (~4g) bullet with a steel core making it a semi-armour piercing round. This was phased out in turn for the M855A1 EPR (Enhanced Performance Round) which was adopted by the Army in 2010. USMC units use an alternative round known as the Mark 318 Model 0 or SOST (Special Operations Science and Technology), a 62gr bullet with a lead/copper core.

The EPR weighs the same amount, also features a steel core but importantly uses a copper alloy rather than a lead core meaning that it is considered to be a more environmental or "green" round. The EPR performs better at penetrating cover due to it’s construction as noted in the link I posted earlier but it also causes higher barrel wear. This is one, albeit small, cause behind the failure of the Individual Carbine program.

The selection of the 5.56mm as the NATO service cartridge was due to several factors: the lighter weight of the cartridge compared the previously adopted 7.62x51mm NATO, higher muzzle velocity and lighter recoil. The lightness of the round meant more ammo could be carried, reduced recoil meant more rounds could be delivered on target and the higher muzzle velocity meant a flatter curve when shooting; making it easier to hit targets up to (what were then) battlefield ranges. Finally, political pressure on the NATO countries from the US decided the matter.

With that, the M193 round was adopted in US Service alongside Eugene Stoner's ArmaLite AR design as the M16 despite British protestations that the round was too light. We (the Brits) had been experimenting with a mid-sized round, between the 5.56mm and 7.62mm designs that offered significant benefits over the lighter cartridge. But more on that later!

The 5.56mm round is a "spitzer" design (short for spitzgeschoss - meaning "point bullet") rather than a round-nosed design. It also has what is termed a "boat-tail" meaning that the bullet tapers back inwards at the rear end before cutting off. The design of the bullet gives it good aerodynamic performance but as noted above it is both a lightweight round and has a long cross section meaning winds could be a major issue if it were not for the stabilisation imparted through spinning the round at very high velocities.

Which leads us to…

Barrel Length
Simply put, barrel length determines muzzle velocity. With a barrel of length X you will get a Muzzle Velocity of Y. By reducing or increasing X you will also reduce or increase Y up to a maximum possible muzzle velocity for that particular cartridge. Each cartridge has a barrel length which is most efficient for generating velocity, over this length and the cartridge will gain no benefit, shorter than this length and it will be less efficient with a lower muzzle velocity.

This can be seen very easily in the difference between pistol calibre firearms. The 9x19mm Parabellum round fired from the 4.25” barrel of a Heckler & Koch USP 9 has an MV of ~390m/s. The exact same cartridge fired from the 8.9” barrel of an H&K MP5 has an MV of ~400m/s. For the 9mm Parabellum round this optimal length is around 16”. Unfortunately the optimal barrel length for a cartridge’s MV is not often the same as ideal barrel length for the weapon design. A barrel of sufficient length to maximise MV is often going to be too long to manoeuvre and the increased inertia will make the weapon harder to transition between targets.

The original M16 rifle adopted by the US military uses a 20” barrel (at this point you might be thinking – why do we keep switching from metric to imperial and back? Welcome to the wide world of firearms!). Each new iteration of the M16, from the original M16 through to the M16A4 has retained this 20” barrel length although it has been a significantly thicker and heavier barrel from the M16A2 onwards.

The current infantry small arm issued is the M4/M4A1 carbine which has a significantly shorter barrel – around 14.5”. Other AR-style weapons such as the Mark 18 Model 0 (aka CQBR – Close Quarter Battle Rifle) go shorter even that this, down to ~10”. There are even AR-like “pistols” like the Olympic Arms OA-93 with barrel lengths down to 6.5”. Civilian ARs generally fire cartridges a little less “hot” than military weapons but most manufacturers now offer milspec parts to allow the use of the NATO ammo without the threat of dangerous malfunctions.

Civilian rifles have a minimum legal barrel length of 16” in the US. This is often skirted by using a shorter length barrel (e.g. 14.5”) but then pinning and welding an extended flash hider which makes it up to 16” overall. It is also becoming more common for civilians to buy and use suppressors nowadays for environmental noise issues, reduction of hearing damage and tacticool accessorisation. Some suppressors actually increase the muzzle velocity of the bullet via an effect called freebore boost.

From this it is easy to see that if a 20” barrel of the M16 is already not getting optimal MV then weapons which are shorter still will be losing a considerable amount of their possible MV. This has an effect that I’ll cover in just a wee moment, after I cover…

Barrel Twist
Barrel twist refers to the distance within the barrel over which the bullet will complete a full revolution as it contacts the rifling. It is normally shown as something like 1 in 9” RHT – this translates to the projectile revolving one full time within a length of 9” with a Right Hand Twist to the spin. The tighter the twist, the more spin is imparted to the projectile on it’s exit from the muzzle. Higher spin means better projectile stability which gives better, more predictable and importantly repeatable accuracy at range.

If the twist is not high enough, the round will be unstable on exiting the muzzle. The round may almost immediately yaw and veer off in a random direction or keyhole (i.e. enter the target sideways on). Too high a twist and you may increase barrel wear and cause minor imperfections in the bullet’s casting to have a major effect. Some lightweight rounds (~40gr) fired at high velocity with too high a spin may even break apart on exiting the barrel.

The ideal twist rate, paired with the right length barrel and the right bullet will have gyroscopic stability which means that the projectile will go where you want it to, maintaining it’s tip-first orientation regardless of the arc at which it has been fired. To work out the ideal twist rate for a specific cartridge you can refer to a formula created by George Greenhill back in 1879. Newer version of the formula (such as the Miller Twist Rule) give slightly more accurate results but the Greenhill Formula remains accurate enough for use to this day.

The original M16 used a 1 in 12” twist with the M193 cartridge. The M16A2 introduced a 1 in 7” twist with the M855 cartridge which was maintained through to the A4 variant and is also used in the M4/M4A1. Civilian AR variants often use a twist rate of 1 in 9” but nowadays with the fetishisation of the military, a lot of shooters are changing to 1 in 7” barrels to best emulate their idols.

Summary
To summarise the massive amount of text above, the M16 was designed to use the 5.56mm NATO round. This round ideally should be fired from a long barrel (>20”), at a high velocity (>900m/s) and with a fast spin (1 in 7” or 1 in 8”) to offset the light weight of the projectile. When these conditions are met, the projectile is highly accurate and stable out to long distance.

When the bullet impacts a target at a sufficient velocity (>760m/s), the M193’s light weight, shape and construction caused the projectile to yaw and fragment after penetrating soft tissue. This could cause simply horrific wounds. The introduction of the heavier semi-armour piercing M855 bullet actually reduced yaw and tumbling trading tissue damage for armour penetration.

So from this we can see that the AR/M16 system is pretty great – I’m not getting into the nitty-gritty of the AR’s gas system (yet) but essentially you’ve got the right round, the right barrel length and the right twist to have the desired effect on target. The problem comes from what happened next.

The Problem?
The M855 was adopted when NATO was facing hordes of Soviet troops and the capability of penetrating a steel helmet at range was vital. The problem (always the same problem) was that they were fighting the wrong war. When the US started peacekeeping and counterinsurgency operations after the Cold War ended, troops began to see more action in urban areas where the overall length of the M16 caused problems. The Army’s solution (the Marines retained the M16A4) was to adopt the M4 carbine.

As noted above, the M4 uses a 14.5” barrel and has several advantages over it’s bigger brother which make it great for MOUT (Military Operations in Urban Theatres). It’s shorter, lighter and thus more manoeuvrable and, importantly, it shares a lot of parts with the M16A2 that preceded it. All should be good then except the shorter barrel length reduces the muzzle velocity of the 5.56mm round to the point where after around 50m from the muzzle it no longer offers the same wounding capabilities. Not only does the round now have have insufficient velocity but it's also spinning less since it's had less barrel length to travel down. This combination significantly reduce the lethality of the M855 round. Now it didn't spin fast enough or travel fast enough to have the desired effect.

Anyone who has read Mark Bowden’s Black Hawk Down may recall that Rangers and Delta operators issued with the M855 (referred to as “green tips” in the book) complained about it’s failure to sufficiently incapacitate a target, even after multiple hits. Since the round was designed to punch through armour, shooting a starving Somalian wouldn’t cause incapacitation. This was due to the change in platform from M16A2 to M4 and the adoption of a round that was designed more to penetrate steel helmets than human tissue. The bullets would often pass straight through the target.

The urban combat of Iraq was one thing, but worse still are operations in Afghanistan where the lightness of the M4 is no doubt appreciated but the short effective range became a major issue. Taliban fighters using all sorts of longarms from AK derivatives to WWII era Lee Enfield rifles have huge range advantages and it is only their poor firearms maintenance and lack of training that keeps small arms casualties at a relatively low level.

The solution to the problem of the M855 and M4 carbine combination were first addressed by Special Mission Units whose mission requirements allowed them greater leeway in the selection of ammo. Many adopted the Mk 262 Model 0 or Model 1 rounds, a 77gr (~5g) bullet that was significantly longer than either the M193 or M855. This bullet gave up the steel penetrator and it’s armour piercing capability in order to bring back sufficient performance against soft tissue. This round was very popular amongst SMUs and once this came out it became virtually impossible to source the ammo.

This was particularly a problem when the guys working for PMCs in Iraq ended up buying nearly every available round for it's "cool" halo effect - they had shitloads of cash and if that was what the high speed, low drag operators were using then they wanted that too. They ended up buying so much of this ammo that the SMU guys they were trying to emulate couldn't get hold of it.

There's more to come if anyone is interested - I haven't got to the Pentagon failing to procure a replacement despite 30+ years of trying and the associated costs, nor have I covered the SOST and EPR rounds in detail as well as the quest for a middle of the road replacement. It's taken me most of the day to bash this out at work (with very annoying filters) so apologies for the lack of links and supporting data.

I'm happy to have any errors pointed out to me. I am at best an interested amateur and I do live in a country where guns are a touch hard to come by. If anyone is even remotely interested I'll try and follow up on some of the things I've partially covered and other related stuff later tonight.
posted by longbaugh at 7:57 AM on June 25, 2013 [11 favorites]


That was pretty fantastic, longbaugh. The stuff about M855/M4 barrel length and the knock-on effects of reduced muzzle velocity I'd picked up on from Fackler's 5.56 fragmentation study and, yeah, Black Hawk Down. But I'd never even heard of EPR, Mk 318, Mk 262 Model 0 or literally anything in the last few paragraphs, especially the bits about the PMC-induced ammo shortage.

Thanks a ton for writing all of that, one of the best-written summaries of the subject I've seen anywhere.
posted by Ryvar at 8:02 AM on June 26, 2013


The original military 5.56mm round was designated the M193 and used a 55grain (~3.5grams) bullet. This was based on the .223 Remington, a lightweight round used for hunting small to medium varmints such as coyote. In the 1970s NATO decided on some small changes to the 5.56mm due to changes in requirements.

A minor point, but this is actually backwards. The original cartridge was the 222 Remington magnum. The military made some modifications for manufacturing and more importantly, reliable functioning in a semi auto rifle with a direct impingement gas operating system (more on this later*). After the military adopted this as the 5.56x45mm round, Remington started marketing the same round as the 223 remington. Over the years some differences have crept in between the military and the civilian version of the cartridge to the point that they are now effectively different chamberings.

*One of the idiosyncratic parts of the AR-15/M16 rifle is how the gun uses the energy of the cartridge firing to cycle the action. On most rifle cartridge semi automatic and/or full automatic firearms the rifle uses a portion of the gas pressure generated by firing to eject the empty brass casing and load the next round. This is typically done by drilling a (very) small hole in the barrel and diverting a (very) small portion of the gas to drive a piston that pushes on the bolt and cycles the action. By using a piston this keeps the very hot and somewhat corrosive gases out of the receiver keeping it cooler and cleaner.

In the AR-15 system there is no piston and those high pressure gases are routed directly back into the receiver to push on the bolt carrier directly. This keeps the gun lighter, eliminates some moving parts, makes manufacture simpler and faster and greatly reduces the amount of mass slamming back and forth while the action cycles which makes the gun much more controllable under full automatic fire. However the guns gets hot fast and it gets dirty fast.

Cleaning is important to all firearms but due to this feature of the AR-15 it is absolutely imperative to keep the gun running correctly and reliably. Early on in its adoption, the us military didn't understand this and to save a few bucks used a type of powder in its ammunition that burned much dirtier and left more residue and didn't issue enough cleaning kits and train the infantry in how important it is to keep the action clean in its new, plastic, light weight rifle.

This is the origin of the reputation for unreliability of the AR-15/M16. The newest thing for the civilian AR-15 market is adding a piston to the action, effectively negating the lightweight advantage and low cost of the AR-15 design was optimized for.
posted by bartonlong at 4:53 PM on June 26, 2013


Company Sells Pork-Laced Bullets Designed To Send Muslims To Hell

This, it seems, is not a joke.


Unfortunately this is not a joke, it is real ammo you can buy. It will be bought by idiots who think they are making some kind of useful statement about how they feel about Islam.

There are a few 'joke' ammunition makers/types out there but I sure wouldn't want to have to explain to the prosecutor why I felt it necessary to use 'joke' ammunition should I ever fire the gun in self defense, or even had any in my possession. My experience within the gun community about this stuff is that most people in the gun store will pick it up (the gun store owner will typically have a couple of boxes they got for free as a promotion), chuckle at the audacity of it, then put it back down recognizing the 1. idiocy of it 2. waste of valuable money you could spend on something useful, like ammunition to target shoot with.
posted by bartonlong at 4:59 PM on June 26, 2013


Can anyone explain why ammunition has such weird sizes? 5.56mm? 7.62mm? Even the Imperial measurements are oddly precise: why .45 inches and not .5?
posted by Joe in Australia at 5:04 PM on June 26, 2013


Because they are that exact in their differences! The difference between a couple hundredths of an inch in width or a couple dozen grains of weight can make a large difference in ballistics. People came up with ways to manipulate bullets to be longer or shorter or heavier or faster by adding or shaving tiny increments of measure until it did what they wanted it to do.
posted by The 10th Regiment of Foot at 5:33 PM on June 26, 2013 [1 favorite]


They are that precise, but a lot of times the well-known name is a marketing thing. If you took a pair of calipers to a .223, it would actually be .224 inches in diameter.
posted by the man of twists and turns at 6:07 PM on June 26, 2013


If you took a pair of calipers to a .223, it would actually be .224 inches in diameter.

It's worse than that! The 7.62 mm diameter of an AK round (7.62 x 39) is often closer to .314 inches, while the 7.62 mm of an M14 (referred to here) is often closer to .310, but the M14 round is commonly called a .308 and another bullet with a .314 diameter is called a British .303, go figure! The truth is though that the caliber sometimes refers to the "lands" and sometimes the groves of the rifling in the barrel and not always the bullet diameter which ranges ever-so-slightly wider than the lands so that the bullet smooshes in and makes a nice gas seal inside and shoves it out along the groves imparting the spin.
posted by The 10th Regiment of Foot at 6:30 PM on June 26, 2013


Can anyone explain why ammunition has such weird sizes? 5.56mm? 7.62mm? Even the Imperial measurements are oddly precise: why .45 inches and not .5?

Most of the oddball metric sizes are the result of converting fractions of an inch to millimeters.
7.62 is .30 caliber-which is a very popular historic size in Britain and US (don't know why over other sizes or more common European sizes already in use at the time). 5.56 is .22 caliber-the typical small game/varmint round size (don't know why .22 was chosen over .20 though).

There are lots of common sizes of calibers in whole/half metric sizes. 7mm (.284") is a very common size in Europe and US, 8mm (.323") is also very popular in Europe (and kinda obscure in the US). 6.5mm (.264) is fairly common. And just to show how arbitrary it can be the old swiss army round was 7.5x55 but the bullet diameter is the common in the US but not Europe .30 caliber or .308 to be exact.

There is no set, common, accepted nomenclature for ammunition sizing, most of the names are just a marketing exercise. However the most common rounds in the US were almost always first a military chambering before widespread civilian use dating back to the .45-70 (a .45 diameter bullet with 70 grains of black powder behind it), to the .30-06 (a .3 diameter bullet adopted in 1906) to the 7.62x51 (a .3 diameter bullet with a brass case length of 51 mm-also called the .308 Winchester) to the 5.56x45/.223 Remington.
posted by bartonlong at 7:19 PM on June 26, 2013 [1 favorite]


bartonlong pips me to the post about the direct impingement gas system of the AR series of rifles (mostly because I'm extraordinarily late in posting a follow up - I'm writing it - cub's honour!). The reliability issues stemmed from several factors, the US Army's refusal to make recommended changes, poor training before deployment, partial maintenance kits, different powder from that recommended by the manufacturer and a host of other things. There was no one person to blame as across the board the adoption of the AR was mired in arguments both for and against it's adoption and this was mirrored in the schizophrenic way in which it was issued.

Quick fun fact for you here - the last time the US Army had a weapon it actually wanted and liked was the M1 Garand (and even that is debatable). Since then the Pentagon has essentially mended and made do with the AR series, to the point where it's now been in service with US Armed Forces for over 60 years and is predicted to remain in service in it's current or slightly amended form for another 30 to 40 years.

That might sound faintly ridiculous as 100 years on you'd think the weapon would be totally outclassed by more modern arms. Keep in mind then that of the other weapons used by the US Military, the .50 Browning Machine Gun has been in service since 1933 and the .45 ACP M1911 Colt* and it's derivatives since (surprisingly) 1911. The second longest serving rifle, the .30 Cal M1 Carbine, was adopted in the mid 40s and served in National Guard armouries through to the mid 70s. Product Improvement Programs offer minor updates and reduce the need to retool and most importantly, like in any political process, lobbyists influence those in positions of power to continue paying out rather than let their golden goose ticket expire.

*No longer the official service sidearm but used by virtually all SMUs. You'll note that no other nation has adopted the M1911 and retained it through to the 21st Century. This is one of those guns like the Colt SAA that is popular more for it's cachet than it's actual use. I've used a 1911 and whilst it is a very comfortable weapon with a simply great trigger, most 1911 enthusiasts will tell you it's the best combat handgun. To actually get it to the point where you can say that with a straight face you pretty much have to have blown a couple of thousand dollars on it. There really are better out of the box .45 ACP handguns so it is pretty much a cultural thing now, logic be damned. I fully expect someone to defend it even here ;)

Back to writing the 2nd epic part about the history of the AR and the 5.56mm now. Back soon (ish).
posted by longbaugh at 12:23 AM on June 27, 2013


all this reminds me of a bit in Cornelius Ryan's The Last Battle. The militia troops organizing to defend Berlin against the Soviets have few guns of wildly varied type and most not chambered for little ammo they've got. So through trial and error they figure out which rounds can be made to work in which guns. As I recall (I don't own a copy) his sources recalled some nervousness at actually trying to shoot like that...
posted by lodurr at 3:20 AM on June 27, 2013


Just to let anyone who is on tenderhooks know - this "potted history of the AR15" is currently sitting at ~2000 words and that is at about 50% of the final length. I personally think that's a wee bit big for a single MeFi comment. If anyone is still interested I will be happy to post it, split it up into chunks, MeMail it or summarise it with a decent bibliography or list of links. I would probably recommend picking up one of the many good books on the subject as an alternative as they will benefit from decent fact checking and an editor...
posted by longbaugh at 6:14 AM on June 27, 2013


the M1 Garand (and even that is debatable)

A ten pound service rifle with a solid wood stock (made from an endangered hardwood no less in order to actually ADD weight and reduce the massive recoil from the .30-06 round) that can cut off thumbs when loaded too quickly, has it's own cycle failure issues, and conveniently rings a bell telling your enemy when it's run out of ammo, yeah, I'd put that in the "debatable" category! (Not that they aren't awesome especially compared to what the other WWII combatants had!)
posted by The 10th Regiment of Foot at 6:46 AM on June 27, 2013


*No longer the official service sidearm but used by virtually all SMUs. You'll note that no other nation has adopted the M1911 and retained it through to the 21st Century. This is one of those guns like the Colt SAA that is popular more for it's cachet than it's actual use. I've used a 1911 and whilst it is a very comfortable weapon with a simply great trigger, most 1911 enthusiasts will tell you it's the best combat handgun. To actually get it to the point where you can say that with a straight face you pretty much have to have blown a couple of thousand dollars on it. There really are better out of the box .45 ACP handguns so it is pretty much a cultural thing now, logic be damned. I fully expect someone to defend it even here ;)

As I understood it (and please correct me if I'm mistaken, I've never seen an authoritative source for this) the popularity for .45ACP in SMUs stems from the fact that it's the only "mainstream" cartridge with an off-the-shelf subsonic muzzle velocity, which means you're a good suppressor away from an extremely quiet system. No need to source specialty low-power rounds to avoid the crack of the sound barrier breaking.

And of course .45ACP is going to deliver a bigger hit at subsonic velocities than low-powered 9mm loads...
posted by Ryvar at 9:34 AM on June 27, 2013


Oh and longbaugh I'd love to see what you've written - either here in chunks or MeMail.
posted by Ryvar at 9:36 AM on June 27, 2013


A ten pound service rifle with a solid wood stock (made from an endangered hardwood no less in order to actually ADD weight and reduce the massive recoil from the .30-06 round) that can cut off thumbs when loaded too quickly, has it's own cycle failure issues, and conveniently rings a bell telling your enemy when it's run out of ammo, yeah, I'd put that in the "debatable" category! (Not that they aren't awesome especially compared to what the other WWII combatants had!)

In the strange world of the military not getting quite what it wanted the original Garand designed his gun around the .270 peterson round (pretty much identical to the 270 winchester round that is itself a 30-06 cartridge with the neck reduced in size to fit a .270 diameter bullet). This change to a larger caliber is why the garand rifle holds the unusual number of 8 rounds in its magazine, while most contemporary rifles held either 5 or 10. The 'clip' system used by the garand actually allows for faster reloads than a detachable magazine, at the price of more complexity in the firearm and less ability to reload individual rounds.

A product improved version of this gun is still being used in limited issue today as the M14 by infantry teams who need longer range than the .223 round can deliver. The Garand design was modified by adding a detachable magazine and changing the gas powered semi automatic function type from an operating rod (kinda like the piston system I described earlier) to a gas tappet operating rod (taken from the M1 Carbine, actually and also used in the very popular ruger mini14 rifle) and inventing a new cartridge that utilized a newer powder design to deliver the same power as the .30-06 in a shorter cartridge. This two modifications made the gun more reliable and more suitable for full automatic fire. Ironically, it was found in practice that the 7.62 round the M14 is chambered for has far too much recoil to be manageable in a rifle in full automatic fire, and the currently issued rifles are all semi automatic fire only (as are the civilian versions called the M1A).

On the cartridge thing, it seems like the ideal cartridge for an individual soldier with a select fire rifle in most studies I have read is somewhere around the 6.5mm-.270 range. However very few countries every adopted this officially and the few that did have since adopted a different size for political reasons. Most recently there has been a flurry of new chamberings for the AR rifles with the two that have found some success being the 6.8mm (this is .270) SPC (Special Purpose Cartridge) and the 6.5mm Grendel. Both of which deliver much improved flight and terminal ballistics than the .223 with manageable recoil and reasonable weight per round and existing rifles can be readily modified to use (included the magazines).

The 6.8 SPC was developed as part of a product development initiated by the US special forces command to find a more effective round than the .223 for their infantry and it examined a very wide range of cartridges with the only limitation being they had to be within a size that would fit in the existing m16 rifles with the only change being allowed to a different barrel size.

The British found in their post world war II rifle development (to replace the Short Magazine Lee Enfield rifles chambered in .303 British that had been in service almost 80 years by that point) that the ideal round for a selective fire weapon was 6.8mm (i forget the exact name of the round and I don't have access to my Cartridges of the World book at work).
posted by bartonlong at 11:01 AM on June 27, 2013


Every time I see the title of this thread in Recent History, this mashup starts paying in my head.
posted by homunculus at 11:21 AM on June 27, 2013


Activity. Gah.
posted by homunculus at 11:32 AM on June 27, 2013


Bartonlong just keeps getting in before me with the right answer but he is thinking of the EM2 in .280. I cover this in the huge wall of text which I have written. Will do my best to post it tomorrow.
posted by longbaugh at 11:33 AM on June 27, 2013


if anyone is still reading this thread, I just found this website that has great charts for all guids of cartridges.
posted by bartonlong at 2:11 PM on June 30, 2013


I recommend Jane's Ammunition of the World but it's a fairly hefty pricetag ($499!) and occasional typos do slip by the editors.

Ryvar - the .45 ACP is pretty handy for suppressed weapons as it's already subsonic and doesn't require cold-loading or suppressor wipes to slow the projectile so the cartridge kind of lucked out as it was already available in large amounts amongst existing units. The Offensive Handgun Weapon System (OHWS) project was created with the .45 ACP in mind from the get go for this reason. H&K won the contract with the Mark 23 Model 0 although most of the folks it was developed for have been using the USP Tactical in .45 ACP as it's shorter and lighter. Since the one was based on the development of the other this is no real problem. The German KSK use the USP in .45 but outside of US SMUs nobody uses a 1911 basis because it's old tech and doesn't have the cultural inertia of the 1911.

The use of .45 1911 derivatives with US SMUs on the other hand (usually Wilson or Kimber models with a sprinkling of Springfields and other self-purchased versions) has slowed down considerably. CAG (AKA Delta, SFOD-D etc) for example issue .40 S&W Glock 22s as they're more reliable in sandy conditions than the 1911. The USMC still uses the MEU (SOC) 1911 although a MARSOC 1911 was developed just before the invasion of Iraq (but I seem to recall it not being adopted in large numbers).

Adoption of newer .45 ACP handguns with higher capacities (e.g. Glock 21, FN FNX) is likely since they have double the capacity of the normal 1911 with increased reliability and customisation from the factory such as barrel threading for suppressor mounting, under barrel and frame top rails. UKSF have stuck with 9x19mm SIGs such as the P226R. Glocks appear to be pretty much the go-to handgun amongst the military at the moment, the British Army having recently adopted the Model 17 Gen IV in January of this year.

I haven't forgotten the rest of the promised post - I have been snowed under with other stuff but I will definitely get around to it soon.
posted by longbaugh at 6:05 AM on July 1, 2013 [1 favorite]


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