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.
I'd suggest starting from scratch and go right through the whole assembly again before you wear the barrel out out. Most of my time with a new rifle or barrel is spent going over everything before even firing a shot.
Is the rifle assembled in a stress free state?
Can you check the bedding of action to stock, if not rebed, particularly if it's a timber stock.
Check the bolt handle does not touch the stock when closed, if so adjust for clearance.
See that the barrel channel is open and not touching.
Look at the barrel crowning for damage during shipping.
Fit the scope which has been centered by a scope technician and bore sight adjusting the mounts to nearly put the scope on target
Check the scope mounts for fit to receiver, lap the rings and epoxy bed the bases to the receiver.
Go to the range and fire one shot,then adjust the scope cross hairs to the bullet hole you fired.
Start your barrel break-in procedure and you should be right on target after firing less than 5 shots knowing the rifle is assembled well.
To assist having a stress free assembly don't tighten screws so that they buckle or bend anything.
The final tightening is done after the epoxy between the components has cured.