Ken Nelson

Competitors can teach the Army about cool and clean running M16s
Shown: The JP Rifles JP-15 AR.

The NY Times covers the Army’s attempts to build an M4 (shorter variant of the M16) that won’t jam:

Watch the video closely. After several magazines, the barrel smolders. Then it becomes red hot. After 1 minute and 20 seconds the barrel begins to droop between magazines — like a piece of warm licorice. Then comes the catastrophic ending, at 1 minute and 51 seconds and after the 535th round, when the barrel ruptures.

They Army has decided to make the barrel heavier to help avoid the problem:

The barrel gets hotter and hotter, and the heat spreads throughout the weapon. The shooter wears a heat-resistant glove even to pull the trigger. Soon the barrel smolders and glows, but it does not droop and does not rupture. At 2:22 the hand guard assembly catches fire. It burns for about two and a half minutes. But the rifle keeps firing, magazine after magazine, until it stops firing on automatic at 4 minutes and 47 seconds, after 911 rounds.

In my experience fouling, not shooting too much/too fast, causes most M16 jams.  Although I have seen M16 barrels begin to get soft from heat, this was before the introduction of the 3-shot burst automatics the soldiers of today use.

The M16 runs very dirty because the gas used to blast  the bolt back to cycle a new round comes directly back into the receiver depositing all sorts of nasties that collect quickly there.  Shoot a 100 rounds through an M16, or AR-15, then put your finger in there and it comes back black.

Competitive shooters don’t risk their lives due to jams, but they do risk losing, which motivates them to modify the guns to never jam.  Most serious competitors in multi-gun, or 3-gun, shooting (pistol, shotgun, carbine) have moved to a gas-piston system of cycling the action. In this approach the gas doesn’t go all the way back to the bolt, instead it operates a piston that moves the bolt. The action runs clean and cool. You can go a 1000 or more rounds and not have to clean the action (you should clean the barrel to extend its life however).

These systems also typically minimize the bolt slap against the back of the receiver.  Most AR-15’s come back too hard, making recoil much worse than need be.

The Army, IMHO, would be better served moving to a clean running, lower recoil, gas-piston variant of the M16/AR-15.   The guns would jam a lot less.  And valuable soldier time wouldn’t be wasted cleaning the weapons.

I’d note that soldiers given a choice, usually in Special Ops or other specialties, generally prefer the gas-piston systems. Reliability plus less maintenance and lower recoil… you can have it all!