I was thinking of using the Ranier Arms 12.5" ultra match 308 bbl for a receiver set I form 1'd. POF, PWS, Sig, Noveske, soon hopefully LWRC, all make 12.5" 308. Bushmaster might. Scar 17 13" would be sweet. You might be better off buying a receiver set, not all 308 uppers like to play together.
Scott