10-07-2011, 10:53 PM
I know that a deformation on your gas port can cause accuracy to go to crap. I just bought an SPR barrel made by the guy who used to do them for Crane. They use Douglas premium air-gaged pipes, and it grouped 1/2 MOA for the 1st 200rds, then opened up. Borescope analysis revealed a large deformation at the gas port from erosion, with a protruding piece of the erosion into the bore. It was tearing into the bullets as they went down, and damaging them enough to jack up the accuracy really bad. Still haven't decided what to do...final finish from Tubbs....?? I doubt lead-lapping will smooth out hardened steel. Really sucks!