Originally Posted by mjkeat
The threads and diameter of the portion that is threaded is the same. Before the release of VLTORs A5 guys used their .308 receiver extension on AR15s to get an A2 like buffer system with the ability to still have a collapsible stock.
Thanks, MJ, good info as fsted2a said. Way back in the 1950s you'd think ArmaLite would have used the same receiver extension threads for the AR-10 and AR-15 (no reason not to since the AR-10 was first and the same tube could be used in the scaled down AR-15). And why not carry forward to the new ArmaLite company AR-10B, DPMS, BM and RRA but you never know until someone tries it.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek