Originally Posted by
Stan_TheGunNut
People are not saying that you can't hit something at 200-300 meters with a 10.5" SBR. They're saying the bullets fragmentation (thus terminal ballistics and wounding potential) will be virtually non-existant at that range with a 10.5" barrel due to the loss of velocity. This is different than just punching holes in paper or making steel clang.
Regarding the OP's original question...I think a 12ish inch SBR is a good compromise. Still short, but better terminal performance. I personally have a 10.5" SBR in 5.56mm. It's completely reliable with everything I"ve put through it, both with and without silencer attached. I've put ~600 rounds through it, everything from Wolf to Hornady 5.56 TAP. No issues at all so far.