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Weapons: Jammed Rifles And Other Obsessions
   Next Article → MORALE: Pilots Seethe While Supply Sergeants Strut

October 19, 2009: Recently, American mass media stories on Afghanistan fighting provided some interesting misreporting on how weapons operate. It all began on October 3rd, about 300 Taliban attacked a small U.S. base in eastern Afghanistan, near Kandesh and about 30 kilometers from the Pakistani border. There were about a hundred U.S. and Afghan troops (most of them American) in the base. The fighting went on for over eight hours, but eventually the American airpower, and the stubbornness of the U.S. infantry, made the difference and the Taliban retreated, taking most of their dead and wounded with them. Over the next few days, another 40 Taliban were hunted down and killed. The defenders lost eight American and four Afghan dead, plus 24 Americans and ten Afghans wounded. Twenty Afghans surrendered, and one was later executed. Ten more Afghan soldiers were killed in the subsequent search for the attackers.

The mass media reports soon were talking about American assault rifles overheating and jamming. Some of the reports displayed a remarkable ignorance of how military rifles operate. One report had the American M4 rifle barrels white hot with heat. That's a physical impossibility, because of the metal used for these rifles. Long before the rifle barrels turned any color from heat, rounds would automatically fire ("cook off") from the heat, and the barrels would fail (split apart). The reporters also seemed unaware of how automatic weapons handle heat. Assault rifles are built to fire about once every four seconds for hours, without any heat problems. Machine-guns do have heat problems, and are designed with easily removable barrels, so you can switch in a fresh barrel. In short, any automatic weapon will overheat if you put too many rounds through it in too short a time. The troops are taught all about this, and are impressed with the fact that they must either cope with it, or risk death.

There was one thing mentioned in the news stories that has some relevance, and that's rifles jamming (not because of heat problems). This goes back to the decades old argument about replacing the recoil system in American assault rifles. This came to a head (again) two years ago, when the army ran more tests on its M-4 rifle, involving dust and reliability. Four weapons were tested. The M4, the XM8, SCAR (Special Operations Forces Combat Assault Rifle) and the H&K 416 (an M4 with the more dust resistant components of the XM8 installed).

The testing consisted of exposing the weapons to 25 hours of heavy dust conditions over two months. During that testing period, 6,000 rounds were fired from each of ten weapons of each type. The weapons with the fewest failures (usually jams) were rated highest. Thus the XM8 finished first, SCAR second, 416 third and M4 last. In response, the army said it was satisfied with the M4s performance, but was considering equipping it with a heavier barrel (to lessen overheating) and more effective magazines (27 percent of the M4s 882 jams were magazine related.) The army noted that the M4 fired over 98 percent of its rounds without problems. The army had been forced by Congress to conduct the tests. Congress was responding to complaints by the troops.

The XM8 had 127 jams, the SCAR 226 and the 416 had 233. Thus the M-4 had nearly eight times as many jams as the XM8, the rifle designed to replace it. The M4 had nearly four times the jams of the SCAR and 416, which were basically M4 type rifles with a different gas handling systems. Any stoppage is potentially fatal for the soldier holding the rifle. Thus the disagreement between the army brass, and the troops who use the weapons in combat.

In dusty places like Iraq and Afghanistan, you have to clean your M16 and M4 rifles constantly, otherwise the combination of carbon and dust in the chamber will cause jams. The army and marines both decided to stick with their current weapons, rather than adopt an easier to maintain weapon, like the XM8 or H&K 416, because of the billion or so dollars it would cost to switch rifles.

If the issue were put to a vote, the troops would vote for a rifle using a short-stroke system (like the XM8, SCAR or H&K 416). But the military is not a democracy, so the troops spend a lot of time cleaning their weapons, and hoping for the best. The debate involves two intertwined attitudes among senior army commanders. First, they don't want the hassle, and possible embarrassment, of switching to a new rifle. Second, they are anticipating a breakthrough in weapons technology that will make a possible a much improved infantry weapon. This is likely to happen later, rather than sooner, but the generals keep obsessing over it.

Earlier efforts to just get the troops a more reliable rifle have failed. Back in 2005, the U.S. Army's design for a new assault rifle, the XM8, was cancelled. But now the manufacturer has incorporated one of the key components of the XM8, into M4 rifles, and calls the hybrid the H&K 416. Heckler & Koch (H&K) designed the XM8, which was based on an earlier H&K rifle, the G36. SOCOM is using the 416, but no one else is (except for a few police departments).

The XM8 (like the G36 and 416) uses a short-stroke piston system. The M16s uses gas-tube system, which results in carbon being blown back into the chamber. That leads to carbon build up, which results in jams (rounds getting stuck in the chamber, and the weapon unable to fire.). The short-stroke system also does not expose parts of the rifle to extremely hot gases (which wears out components more quickly). As a result, rifles using the short-stroke system, rather than the gas-tube, are more reliable, easier to maintain and last longer.

H&K developed the 416, for SOCOM, at the same time the XM8 was being evaluated by the army. SOCOM got the first 416s in 2004, a year before the army cancelled the XM8. The 416 looks like the M4, for the only thing that has changed is the gas system that automatically extracts the cartridge after the bullet has been fired, and loads the next round. SOCOM can buy pretty much whatever they want, the U.S. Army cannot. SOCOM listens to what its troops want, the army often doesn't. In trying to avoid embarrassment and scandal, the army leadership is blundering into it anyway. Now the issue is getting revived, and is getting more attention from Congress. The army doesn't like that either.

 

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Dave_in_Pa       10/19/2009 10:34:05 AM
The M-16 (and variants) has been the standard US military rifle since the middle of the Vietnam War.  That's a long time ago and technology and engineering keep moving forward.  Time for a change,  I think.
 
There's a very informative article at Wiki on the XM8.  Besides more history and technical info, this also includes more background on the cancellation of the whole XM8 project.  The billion bucks to re-equip Army and Marine infantry with XM8s is pocket change by Pentagon standards, so I suspect the main problem was really political pressure from domestic manufacturers and Army brass not wanting to be embarrassed over the whole thing. Here's the Wiki link. http://en.wikipedia.org/wiki/XM8
 
Any comments from more infantry- and small arms-knowledgeable folks?
 
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YelliChink       10/19/2009 12:10:24 PM

The M-16 (and variants) has been the standard US military rifle since the middle of the Vietnam War.  That's a long time ago and technology and engineering keep moving forward.  Time for a change,  I think.

There's a very informative article at Wiki on the XM8.  Besides more history and technical info, this also includes more background on the cancellation of the whole XM8 project.  The billion bucks to re-equip Army and Marine infantry with XM8s is pocket change by Pentagon standards, so I suspect the main problem was really political pressure from domestic manufacturers and Army brass not wanting to be embarrassed over the whole thing. Here's the Wiki link. link
 
Any comments from more infantry- and small arms-knowledgeable folks?

No, the problem with XM8 replacement is because it doesn't make much sense. Firearms technology hasn't been advanced since 1980s, and the advancement made in late 20th century is marginal to previous one in 1950s. Besides, XM8 didn't pass the rigorous test of US Army. I would argue that a redesigned Ruger AC-556 with forged parts and M14EBR-type stock is better than XM8.
 
No guns are free from malfunction. AK-47 does suffer from failure under negligence despite urban myth. Did Mythbusters bust that one yet? M16/M4 rifles ain't broken. No need to fix it.
 
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JFKY    Dave in PA   10/19/2009 1:18:56 PM
From what I have read here, the XM-8 failed its field trials with the US Rangers.   The hand guards began melting under sustained usage, amongst other problems
 
As Yellichink and Horsesoldier have both written, several times, the advantage of the M-8 or HK 416 and the like or even the 6.8 SPC cartridge is not so great as to justify the expense of re-equipping the US military.
 
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Nichevo    D--d scientific illiteracy!   10/19/2009 1:53:32 PM
I may not be a soldier, but I took physics once.  When metal heats it expands.  But perhaps unintuitively, it expands all over.  Including any holes in the metal - they grow too.  Imagine an annulus (a donut, if you like, or more properly a washer) under heat.  The external diameter grows, but so does the inner diameter - IOW, the hole.  The breech or chamber will not tighten, it will loosen.
 
I will say again what I have always said - a billion dollars is nothing, and there is nothing more important to have than the best possible rifle.  If you want to win wars by taking and holding ground, that is.  A new caliber is needed anyway because of this fondness for short barrels.  I am all Hooray-for-our-side, but that doesn't mean I have to tolerate excuse-making.
 
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doggtag       10/19/2009 3:34:48 PM
Two distinct problems rarely mentioned when guns overheat are gas bleed around the sides of the bullet travelling up the barrel due to barrel expansion, and "keyholing".
 
At such tight tolerances to get a good seal behind the bullet, even a few hundredths of an inch expansion in even only a spot or two can ruin the shot (testing and eval probably demonstrates that the barrel doesn't uniformly expand), so the post was spot-on about barrel expansion being an issue.
 
When there's a gas bleed around the bullet as it goes up the barrel, that's less gas under pressure behind the bullet to effectively work the automatic mechanism when the bullet reaches past the gas return tube.
In the case of a gas blowback weapon like the M16/M4 series, that could equate to not enough pressure to effectively travel back thru the return tube and work the bolt carrier assembly the full length necessary to function properly.
 
 
Keyholing is a result of tube expansion: the bullet doesn't maintain a consistent flight profile on its journey down the barrel due to the gas bleed, and is more likely to tumble more quickly a shorter distance from the muzzle
(it effectively is slightly wobbling as it travels thru the barrel).
I can't currently recall which recent gun magazine featured an article about gun testing that featured a very clear picture of keyholing, where bullets literally were impacting thru the paper target almost sideways.
 
Certainly were a gun to heat up during intense combat duration, that effect will come into play sooner.
Although it may seem like a bullet tumbling in that manner might cause more yaw inside the target (especially at very close ranges where the bullet still has high initial velocity),
not impacting nose-first actually seems to result in considerably reduced target penetration or even entry altogether,
resulting in reduced traumatic wounding effect,
plus the obvious rapid loss of accuracy the farther the bullet travels.
 
 
As to issues of the XM8 rifles being made out of inferior polymer construction to the point they "melted" in trials,
we have to remember that the M16 didn't come to the battlefield without disastrous problems (in Viet Nam) also.
Few weapons ever reach the battlefield without some measure of problems surfacing.
In the case of the M16, its original handguards were constructed of Bakelite, a material that wasn't the most durable under the extreme conditions (battlefield use) it found itself in.
The problem of the original Bakelite construction was made even worse under extreme cold conditions (Arctic warfare), where the material became very brittle (like many polymers do in sub-zero temperatures).
 
So it isn't fair to judge the XM8 to a different standard, is it (poor construction due to original materials used) ?
What weapon system hasn't been upgraded after initial-issue use reveals any flaws in the design?
Obviously the M16 wasn't a perfect child: look at just how many ways the weapon has been modified and improved.
Why should we judge the XM8 or any others to be so inferior when obviously they could just as well be improved and modified as field use reveals any more flaws in those designs?
The issue with the XM8's "plastic" construction was only minor, nothing that couldn't have been corrected.
 
The other whole suck about this rifle argument is: "But the military is not a democracy, so the troops spend a lot of time cleaning their weapons, and hoping for the best. The debate involves two intertwined attitudes among senior army commanders. First, they don't want the hassle, and possible embarrassment, of switching to a new rifle...  "
 
So it would be an embarrassment to the Army leadership to admit that, "hey, maybe we do need a new, better design after all",
yet they're OK with the embarrassment of these arguments and accusations surfacing again and again?
And they're also OK with the embarrassment that maybe just such a weapon with improved reliability just might save a few more troops' lives, yet they're afraid to consider that line of thinking, for thinking it may bring them yet more embarrassment?
Then again, there's still always the , "the troops just need to clean them more often!" attitude...
 
Something else I've noticed about the whole M16/M4 saga: I very rarely see any higher-echelon leaders even carrying any assault rifles. Most of them seem to only have M9s (9mm handguns).
(But rear-echelon troops don't need
 
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WarNerd       10/19/2009 3:52:18 PM

I may not be a soldier, but I took physics once.  When metal heats it expands.  But perhaps unintuitively, it expands all over.  Including any holes in the metal - they grow too.  Imagine an annulus (a donut, if you like, or more properly a washer) under heat.  The external diameter grows, but so does the inner diameter - IOW, the hole.  The breech or chamber will not tighten, it will loosen.

The bolt and cartridge expand too.  It all depends on the relative temperatures of the different parts and their expansion coefficients.  The brass used in the cartridge casing has a higher expansion coefficient than steel and also softens at lower temperatures.  The cartridge is colder than the breach when it is inserted then expands quickly, especially when fired, to achieve an interference fit.  Most jams that are not due to fouling are the result of the cartridge failing to extract from the breach.
 
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ndonovan       10/19/2009 8:19:19 PM
I am not a soldier
 
I think our infantry should have the best equipment available
 
Time spent constantly cleaning a weapon is wasted.
 
Certainly there are situations where there is no time available to clean a weapon.  If you are sitting in a foxhole expecting an attack, I assume you don't take your weapon apart.  Also is cleaning a weapon while laying in the mud really going to work?
 
It seems like the attitude is that soldiers should just suck it up, because part of being a tough soldier is constantly maintaining your weapon and if you don't maintain your weapon you deserve whatever happens.  This seems as archaic as insisting soldiers undergo surgery without anesthesia.  Unless physics and/or mechanics precludes weapons that rarely jam, they should be the standard.  
 
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Slim2None    Norway....   10/19/2009 11:36:31 PM
  Hi there.  New to commenting here, though am a longtime reader of Strategy Page.  Also, not a soldier, or anything else but an interested party, with a passing knowledge of firearms.  Just for the record, the Norwegians bought and fielded HK 416's, apparently not without incident.  You can just Google 'Norwegian HK 416' for more info.  Suffice it to say that the pistons in the recoil system froze in cold conditions. Oooops.  The FN SCAR is actually being fielded in larger numbers than the 416 in various units of SOCOM, and specifically with one Ranger unit, for testing and evaluation.  Word is that the charging handle, which reciprocates with action of the bolt, can cause stoppages if you touch it during cycling.  Which is why a reciprocating charging handle is of questionable virtue in that application.  The point is, the newest, best designs ALL have flaws that will potentially affect users adversely in extreme conditions.  At least the M4's sins are known, not to mention paid for.  I think there are better rifle systems than the current M4/M16 platform, but I also think that they're going to have to be at least a billion dollars better before DOD makes a switch.  And we still haven't discussed the cartridge issues regarding the efficacy of 5.56x45.  Should we switch that, too?  
  It's easy to get worked up about our guys not having 'the best'.  And over the last eight years, this has come up again and again, from body armor to MRAPs.  The media and the Congress get a lot of mileage out of it, and sometimes it actually shapes policy.  But since that kind of thinking is how the military got the M16 in the first place, I can understand wanting to take it slow.  I'm sure they understand that whatever rifle they buy, they're gonna be stuck with for a long, long time.  As such, it better be really, really good.
 
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Slim2None    Norway....   10/19/2009 11:48:32 PM
  Hi there.  New to commenting here, though am a longtime reader of Strategy Page.  Also, not a soldier, or anything else but an interested party, with a passing knowledge of firearms.  Just for the record, the Norwegians bought and fielded HK 416's, apparently not without incident.  You can just Google 'Norwegian HK 416' for more info.  Suffice it to say that the pistons in the recoil system froze in cold conditions. Oooops.  The FN SCAR is actually being fielded in larger numbers than the 416 in various units of SOCOM, and specifically with one Ranger unit, for testing and evaluation.  Word is that the charging handle, which reciprocates with action of the bolt, can cause stoppages if you touch it during cycling.  Which is why a reciprocating charging handle is of questionable virtue in that application.  The point is, the newest, best designs ALL have flaws that will potentially affect users adversely in extreme conditions.  At least the M4's sins are known, not to mention paid for.  I think there are better rifle systems than the current M4/M16 platform, but I also think that they're going to have to be at least a billion dollars better before DOD makes a switch.  And we still haven't discussed the cartridge issues regarding the efficacy of 5.56x45.  Should we switch that, too?  
  It's easy to get worked up about our guys not having 'the best'.  And over the last eight years, this has come up again and again, from body armor to MRAPs.  The media and the Congress get a lot of mileage out of it, and sometimes it actually shapes policy.  But since that kind of thinking is how the military got the M16 in the first place, I can understand wanting to take it slow.  I'm sure they understand that whatever rifle they buy, they're gonna be stuck with for a long, long time.  As such, it better be really, really good.
 
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FormerMarine    Time for a Better Rifle   10/20/2009 6:40:28 AM
Our weapons development and procurement processes are crippled by people that have very little idea how weapons work and what they are used for. Modern weapons are used for both precision fires and high rates of fires, depending on the situation. All weapons develop heat during firing and the higher the rate of fire, the more heat that has to be disposed of. A classic case of the idiocy within the army R&D and procurement process was the M60E3 machinegun: some genius decided that the company's medium machinegun needed to be light enough for "walking fire" and gave an already unreliable machinegun a thin barrel. After the usual millions of dollars expended, the M60E3 was fielded and quickly started melting barrels. I had a whole armory full of S-shaped barrels with holes through the side of the barrel where the bullet exited. Junk - which was quickly and intelligently replaced by the Marine Corps with the more reliable and proven FN-MAG machinegun, the M240G.
 
The M-16 series has always been a least-bidder turkey: the breech is difficult to access, the barrel and receiver are unlike materials (inducing corrosion and allowing bending), the gas system deposits filth into the bolt/receiver and gas into the face of the firer, the gas tube starts glowing after two magazines at full auto, and the caliber is a short range wounder, not a one-shot killer. Despite years and multiple wars to give enough data to substantiate the need for a more effective weapon, the army and the Marine Corps can't or won't make the necessary fiscal and mental investments to give our infantry a more effective battle instrument. Even Eugene Stoner saw the light eventually, designing the AR-18 and the Stoner 63 series of weapons using tappet gas systems and steel construction, but the army and the Marine Corps stubbornly cling to the M-16/M-4 despite the poor battle history and the requests of its users for something more reliable and something with more hitting power.
 
The defense R&D institutions are broken. Their idea of 'improving" the infantry fighting tool is to encase the front of the weapon with rails to mount gadgets - turning a reasonably light weapon into a brick with laser pointers. Their idea of an "advanced" weapon was the Objective Infantry Combat Weapon (OICW) which was a dual-caliber (5.56mm and 20mm), dual magazine monstrocity with a huge sight - that required an accurate lasing of the target before the weapon could set the fuze on the 20mm projectile. Anybody want to be that guy, sticking his head and shoulders above cover for those seconds to get the laser aligned long enough to get an accurate range during a firefight? That projectile supposedly allowed airbursts over the enemy but the very small warhead and tiny fragments would have only have served to annoy the enemy. All this in a 17 pound (unloaded) weapon.
 
It's time for a whole new design of the defense R&D apparatus with experienced operators running things, a real budget, and a whole new look at a family of advanced infantry combat weapons - but I don't have any faith that we'll see that anytime soon. 
 
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