Quote Originally Posted by grizzman View Post
Thanks for suggesting removing the upper for perform the test. I'm "working" from home today and have easy access to the components to test mine. My test involves a Gen 2 Magpul UBR with A5 length receiver extension without spacer, DPMS 308 carbine buffer, Aero M5 308 lower receiver, Aero 308 BCG.

To make things easier, I removed the spring. With a short DPMS 308 buffer from my spare parts stash (which is the same length as my Aero carbine buffer), the carrier does contact the lower receiver before the buffer reaches the end of the receiver extension. With the bolt carrier fully inserted and resting against the lower, the buffer slides forward and backward in the receiver extension freely.

I honestly don't comprehend how this setup.....A5 receiver extension/SR25 pattern BCG/SR25 pattern 308 carbine buffer.....is working well in anybody's rifle. I'm not trying to prove anybody wrong....just don't want anybody, which includes people reading this thread 5 years from now, damaging their rifle.
Agreed! A short 308 carbine buffer in a A5 receiver extension will cause the gas key to contact the receiver during cycling. OTOH, I'm not sure if a standard length carbine buffer will work in an A5 with a 308 BCG or not, but it may.