Hi there, I have a Montana rifle in 300 wby, I just had a #3 Bartlien barrel installed by a very good gunsmith. It has a great tigger and is bedded in the factory Montana stock. I broke the barrel in per the instructions. H-4831, IMR 4350 and a box of factory wby 180 ammo. I can’t get the gun to shoot! It’s a 1 in 10 twist. I cleaned real well with CR-10, then ran JB Bore Paste down the barrel, then cleaned again and oiled. the bullet I’m trying to get to shoot is a 168 accubond long range. The scope is a 4.5x14 leupold, Warne bases and Leupold PRW rings. I loaded a bunch more with IMR 7828, R-19, and AA-3100. Now, by the way, during break in the barrel was very very filthy. I’m hoping that the JB Bore Paste helps. I seat the bullets so it clears the magazine for magazine clearance purposes. All bases, rings and scope are top notch and tight. I’m told that IMR 7828 is the go to powder? Any tips? Maybe takes awhile to break in? I’m letting the barrel cool after a few shots as well. Thanks for any tips at all to get this going.