I have a stag arms 6.8 SPC II 16" upper. Free floated barrel. DPMS lower with Timmney trigger. I have been shooting SSA 85 grain frangible and a 90 grain Speer TNT hand load. Both these shoot fairly well. The kicker is my cold bore shot is exceptionally good. But subsequent shots seem to move an 1.5"-2". And start a whole new group. I can only assume there is some variable in the bolt lockup between when I drop it manually and when it runs it's own cycle. Anyone have experience in this area?