Folks, I think I got a problem here, and need some input. Got my builder back from smith, mounted stock and scope, headed out to break in barrel. First round, bolt closed real hard. Actually sheared/smeared some brass off the head. Touched it off, and the bolt lifted ok. Re chambered ok, and closed again ok. Came out looking clean, no signs of gases anywhere on outside of case. 2nd round closed a little easier, ejected ok, also clean. 3 rd , hard to close, although no brass smearing on head, and powder residu around case mouth. 4th and 5th about the same. 6th round, more residue , farther down the case, and a shiny mark at just above the top shoulder radius, but only half way around. Round 7, hard to close, stiff bolt lift, and more residue. 8th (and last ) round, sounded kinda strange, like tik-bang, lots more bolt lift, shinier half moon around neck, and powder fouling in the rim area. The pictures are of the last shot, I'm just turning the case a little. These are not hot loads, new brass full length sized and trimmed to length hand loads. 338 378 Weatherby. I'm stumped, discouraged, and I'm hoping somebody out there can shed some light on this. Thanks.