Can I Use An AR15 Rifle Length Buffer In My AR10 or 308AR Rifle Stock? That is a question we see pretty regularly on the forum and Facebook. The answer is of course no and the reason is simple. The AR-10 and 308AR Bolt Carrier Group are much longer than an AR15 Bolt Carrier Group. Using the AR15 rifle length buffer would not allow the AR-10 and 308AR to cycle completely.
So now your thinking how can a substantially more powerful cartridge use a shorter buffer? That too easy an easy answer or two. A Rifle Length AR-10 308AR buffer will weigh substantially more than an AR15 Rifle Length Buffer.The AR-10 and 308AR Buffer Recoil Spring will also be stronger offering more resistance. Slash of Heavy Buffers.com does a great job of sorting it out.
Update; Pat Raley our resident AR-10 expert offers up a more thorough and detailed explanation.
The buffers and buffer springs between the AR-10 / .308 style rifles and the M-15 series of rifles are different. Not just length, but weight also. They are both close in size but yet different enough where they should not be interchanged. Now as for receiver extension tubes… (this is mostly for ArmaLite rifles) There are 3, I say again… 3… I spell t h r e e different size receiver extension tubes. The rifle length is the same for the AR-10, as it is for the M-15. The carbine receiver extension tubes are different. The AR-10 is longer to allow the larger bcg to make the distance. In theory. .. you can not use an M-15 receiver extension on a AR-10.
(Another story at a different time)
Carbine…..we will save that for another post at a later date.