Basically plan on building around the Aero M5E1 receiver set, won’t run a barrel yet so I can do the 12.5” 8.6blk from Q. What’re the best “internals” for a short AR-10? Bcg, buffer systems, blah blah. My only experience with an AR10 was buying someone else’s build and his puzzle pieces didn’t go together and caused me tons of issues.