I'm new to the 6.8 as I just purchased my first upper which should be here today. It's a RRA 16 inch with a 1/10 twist rate. It is SAAMI II, so I'm okay in that respect. Anyway, after reading some info on this forum I've learned that the 1/10 barrel builds up unnecessary pressure causing lower than possible velocities. Exactly how much velocity is lost by using a 1/10 with 6 grooves compaired to the 1/11 with 4 grooves? I hope I have my numbers correct. I plan on starting out with the 110 SSA pro-hunters if that helps as a comparision. Thanks!!