Another AR15 question.....

BUCKAWHO

The AR 15 bolt carriers seem to come in three different styles relating to the amount of metal cut away from the underside at the rear. This would seem to affect the carrier weight. Is there any relationship between barrel length and the weight of the carrier? Do longer barrels require a heavier carrier for proper cycling? BT

mark christian

[img][/img]

L-R: M16 carrier, AR, Colt AR-15.

The amount of metal removed is based solely on preventing the carrier from functioning in a lower receiver with M16 internal parts installed. The dimensions of the carrier has no relationship to the barrel length of the rifle.

BUCKAWHO

Thank you, Mark. Your picture shows exactly the carriers that I asked about. All different, but apparently all able to be used in non-military AR15s of any barrel length. Great stuff on this forum!
Thanks again. BT

v35

Carriers having more metal will have greater momentum.
Cycling will therefore be more reliable, especially in shorter barrels which have a shorter pressure duration.

dcs shooters

Some companies are using the "M-16" carriers the slow down the cycle rate in carbines.
It's the only '16 part that is OK with the gestopo [;)]

Txs

There's no direct translation of bolt carrier style to barrel length, as in short barrel/light carrier or long barrel/heavy carrier, but it can factor in.

Proper functioning of the M16/AR is dependent upon a balance of the distance of the gas port from the bolt carrier, gas port size, bolt carrier weight, buffer weight and recoil spring weight.

A change in any one of these five will alter the balance. For example a standard rifle's gas port size shouldn't be used in conjunction with a carbine's shorter port to bolt carrier distance.

Generally speaking though - as long as the other four components are properly set up for it - a heavier M16 carrier will give greater functional reliability.

The final portion of the bolt carrier's forward movement supplies the energy required to rotate and lock the bolt to the barrel extension. The greater weight of an M16 carrier results in increased momentum to overcome this energy robbing portion of the rifle's cycling, which becomes greater as heat and fouling increases.