Recent troop losses in Afghanistan have prompted the usual search for scapegoats and easy or cosmetic fixes. One of the early candidates for scapegoat is the M-4 Carbine.
The M-16 series of weapons, of which the M-4 is one of the latter children, has been trouble prone since inception. Most of these troubles were (and are) a consequence of the gas operating system of the design, which tends to cause substantial carbon deposits to form in the chamber and barrel. This deposition issue seems to be further exacerbated by cold temperatures and high altitude. Dust, which is another known issue, is no worse in Afghanistan than in Iraq.
Despite these known issues, the M-16 family of weapons has done reasonably well in service, and remains popular with most users since it has the twin advantages of lighter ammunition (thus allowing more rounds to be carried), good accuracy, and (especially in the case of the M-4 Carbine) a light and compact form factor. Most of the gas operation woes can be ameliorated by constant and thorough cleaning by the troops who use the weapons.
Amelioration is not elimination.
The systemic problem (gas operation) was addressed in the XM-8 Program by replacing the gas tube with a short stroke piston. Nor did this engineering solution die with the XM-8 Program in 2005. Instead, the designer of the XM-8 (Hekler and Koch) applied the lessons learned from the canceled XM-8 to the H&K 416.
The H&K 416, which is the M-4 with the short stroke piston replacing the gas tube system, has been adopted by U. S. Special Forces, and recently as the new main battle rifle of the Turkish Army, both of which have long experience of mountain fighting in arid environments.
UPDATE below the fold
StrategyPage returns to the subject today:
Jammed Rifles And Other Obsessions
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 just 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 jams from overheating, which causes metal to expand, and provide less room for a new round to enter the firing chamber) 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.