Someone correct me if I am wrong... but isn't the 308 barrel nut larger than a AR15 barrel nut ?
And most likely different threads ?
Yes, I used to be a moderator on a facebook AR-10 builders page, the only thing for certain about the 308 AR, is that nothing is standard.. 308 AR is the catch all phrase for any large frame.. AR-10 is very specifically ArmaLite.. your Smith and Wesson is a DPMS clone, and the Smith and Wesson MP-10 does indeed have some proprietary parts, and does not play well with others.. but then neither does my Wilson Combat WC-10...
That is intentional on Smith and Wessons part, they frown on people making changes to their weapons, which affect warranty and function,,, so don't assume anything, if you read some of my past posts, here on the MP-10 thread, you might get some ideas about those proprietary parts, I believe the BCG is proprietary, and probably the barrel nut as well?? its been a while since I was emersed in the large frame AR rifle, so forgive me. billy
the gentlemen on 308 AR are a wealth of information,, just be respectful,, they may not be, but somebody will help you if you ask nicely, some characters over there, a lot of veteran's, but some very knowledgable gents on the large frame AR.. There is a LOT of good reference material on handguards and barrel nuts, gas blocks, and of particular importance on the large frame AR is the gas port on the barrel... I increased my gas port diameter considerably to get it to reliably eject...
Also large frame AR's are very hard on brass, so if you reload, tolerances are very important, loads and over all case length, etc, etc, blah, blah, blah, blah, blah