starting SBR paperwork.(no, not in Kalifornia) and am undecided on weather to go with a 10.5" or 11.5". and what brand (BM, LMT,CMMG,Colt)i know this brand topic is covered in other threads, but  if there's any issues regarding shorter barrells that's not covered elsewhere and what is ideal setup for function/cycling. i've read about "Fat BOY" tubes, "enhanced bolts" and extra heavy buffers ect. i will want to mount suppressor(Gemtech M4-96D) and use upper on a Machine Gun some time in future.

The 11.5's tend to function better and Gemtech says that is the shortest barrel you should put a can on.

If you’re going to use an M4-96D you ‘re going to have to go with the 11.5-inch or better. The 10-inch won’t give you enough room to push the suppressor on.

I’ve got an old Bushmaster 11.5-inch SBR that runs just fine and has never given any real problems. The barrel there is long enough to have the BiLock and to mount the M4-96D.

I have an LMT 10.5" upper with a bi-lock that I run an SWR Specwar2 on....no problems with mounting the can and my upper has a bayo lug.  But I'm not sure if Gemtech's M496d is longer in the mounting area; I suspect that they are identical.

Josh

A local suppressor manufacturer told me not to use less than 11.5" barrel because there is an increased risk of spontaneous combustion of unburned powder in the baffle stack.  Unburned powder apparently builds up more the shorter you go.  A seller of 10.5" uppers on the EE said he sells lots to contractors who use the Knights' suppressor and they haven't reported any problems.  I went with 11.5"

Josh, that’s great, I had been told that there wasn’t enough room for the suppressor to move back to mount before it would hit the FSB, therefore a 10.5-inch barreled upper wouldn’t work. That’s really cool though, do you have any pics of your set up?