Finally got out to do a little bit of load testing with the SPR upper on my SPR/SBR combo that I put together a little while back and all I have to say is WOW I'm a believer in these barrels now. Its a Larue Stealth 18" in 5.56 with a 1:8 twist, I loaded up some 68gr hornady match over some varying weights of 4320. The best group of the day was the 5 shot group in the first pic measuring at .428" shot at 110yrds. For basically a budget build on the upper with the exception of the barrel, to say that I'm impressed is an understatement!