Extra Three Inches

[recce_o]

I look at the M4 and then I look at the 11.5" barrelled Colt Commando and I ask: "Why is the M4 barrel 3 inches longer?" I think I have two answers:

1. Higher muzzle velocity in the longer barrel.
a. The 5.56 mm depends on velocity for terminal ballistic effect. So the question I have here is whether velocity in the 11.5" barrel is sufficiently lowered that wounding effects are decreased.
b. Increased velocity means greater range. Can anyone comment on the effective range of the 11.5" barrel as compared to the 14.5?

2. Reliaiblity. The extra three inches means that gas pressure is maintained in the barrel longer resulting in a greater gas impulse to the bolt carrier and hence, more reliable operation. However, on the 11.5" barrelled weapon I've used I noticed no appreciable decrease in reliability. Anyone have any comments on the reliability issue?

[TR]

Your correct, and there's also another reason why the M-4 has an extra three inches.

Of cours it is also lenghtned to allow the weapon to use the M-203 PI but that's pretty obvious.

T.R.

[FITTER395]

Another reason:The added length allows the use of a bayonet. The 16" barrel on a civilian "CAR-16"(ha ha)is too long for the
bayonet,but the 14.5" M4 barrel is just right.

LaFrance makes a special gas tube for the short(10"&11.5")barrels;I believe it has an
adjustable gas port.

[Mountaineer]

Reliability is the main key, you hit the nail on the head. I think it was the Marines who originally did the testing but they started with a standard A2 barrel and would cut an inch at a time and test it. They found after 14.5 inches they got unreliable feeding and extraction. You're also right about the ballisitcs issue as well.

[recce_o]

Thanks for the replies. Can anyone quantify the extent of unrealiability? I know it's a hard question, but it doesn't hurt to ask http://www.specialoperations.com/ubboard/smile.gif

The reason why I ask is because I've tried the 11.5" model and didn't find it unreliable. I'm just wondering if I had an exceptional weapons, rather than your average sample.