For the life of me i cannot figure out what is going on. I built a 9LB 338 lapua a few weeks ago and have taken it out and shot it, proof fired and started just shooting a few rounds through it. Was not bad in the sled and got it dialed in. Took an off hand shot a few days later at a coyote and thought hell i better muzzle break it. Turned it down 5/8-24 and put a break on it. Re did the same crown on the barrel and everything seemed fine. Went out shooting with it and although the recoil is easily tolerable now the groups have went from 1/2 moa to 1 1/2 with the break on. Took the break off and shot a few rounds on the sled to see what was going on. Same thing 1 1/2 moa gun. Before it was threaded it was a 1/2 moa rifle with an 11 degree crown, now its a 1 1/2 moa rifle with same 11 degree but threaded. Anyone ever experience this?