Check your twist rate. When you get much above 55 gr a 1:14 to 1:12 rate will not stableize the longer bullets. As for a barrel, check with a local gunsmith. But my preferance is lilja and make sure when ordering to ask for a twist rate of 1:7 to 1:9 to stablize the longer more ballistic efficient bullets like the 80 gr hornady a max with a bc of .453.gun)
