[OldSmaj]

It was only when they shrank it to AR-15/M-16 size that the fouling issues came up.

Would that have more to do with the shortening of the gas tube or the closer tolerances of the bolt/chamber?

I tend to think that the closer tolerances, necessary to withstand the 28,000 psi chamber pressures, had much to do with the jamming issues.

I carried an M-14 in 'Nam, but I'm aware of some that carried the M-16, that learned that a nearly worn-out action jammed much less.

They'd refuse to turn them into the unit armorers for just that reason, even when you could hear the bolt rattle in the receiver like a tin can with pebbles in it.

I'm not sure and I don't claim to be a M-16/AR-15 expert and I never took an M-16 to war.

But every time I qualified with it, the damn thing would jam at least once with me, unless I kept it full of BreakFree.

Beats me.

[Leisler]

The 16 was a system. It was designed to fire with a special type of powder. The military only had one type of powder, universal to all small arms. This powder would build up and foul the M-16. This was well known.

The M 16 was not designed by the Army's small weapons bureaucracy. So, to justify their existence, and to get back at the embarrassing advance design of M-16, they let the program go forward with a bullet fuel that they knew would cause the weapon to fail, and thus justify their existence. Dead soldiers be damned.

Nice, huh? My experince with Army equipment bureaucracy is that it is at least a decade behind. Still, it's a nice, secure job if you can get it. Just don't be a front line trooper.

[marktwain]

The rifles were tested with the ammunition that Stoner designated them for using IMR propellant. After the Army adopted them, the ordinance branch changed the propellant to a ball powder with quite a bit more calcium in the mix.

It was the extra calcium that collected in the gas tube and caused the fouling that cause jams. It was all written up in the American Rifleman in the '80s. If the Army had kept the same ammo formulation that Eugene Stoner had mandated for the rifles, they would have had an excellent reputation for reliability.

[tanuki]

"I carried an M-14 in 'Nam, but I'm aware of some that carried the M-16, that learned that a nearly worn-out action jammed much less.

They'd refuse to turn them into the unit armorers for just that reason, even when you could hear the bolt rattle in the receiver like a tin can with pebbles in it."

That makes a lot of sense. The reasons for the AK-47's legendary reliability are its extreme simplicity of design and its loose tolerances. Together, they make up a robust weapon system that may not past muster at Camp Perry, but will work in conditions that will kill more sophisticated arms.