Armalite AR10 carbines use an 8" carbine buffer tube vs. the AR15's 7.5". They use a H3 buffer that is the standard AR15 size. Not the DPMS shortened buffer version. The DPMS LR308 use an AR15 length buffer tube. All AR10 use same spring. You can buy AR10 buffer tube, spring and H3 buffer from DSG Arms as well as other places for a decent price. You could also buy a POF 8" buffer tube with the "shelf" to help eliminate carrier bounce. My 2 cents.