Re: 12bvss .308 not grouping
Sounds like maybe a problem with barrel binding in stock, after a couple of shots warm everything up. Check that the actions screws are torqued properly too. Something is trying to move and it is not being allowed to somehow would be my first shot. The scope could be an issue, but with it group the first two shots every time, I don't think that is the issue. Has the gun been glass bedded?
Re: 12bvss .308 not grouping
It isn't uncommon for the bullet POI to shift some from a brake so you might try shooing groups without the brake to see if the groups get more consistent.
I would avoid shooting off a bipod if at all possible. It creates harmonics that can ruin a guns accuracy especially if shooting off a hard surface like a bench. I have a rifle that shoots well under 1/2 MOA and when fired off a bipod it is well over 1 MOA using the same bullets on the same day.
I agree with McKinneyMike, I would definitely make sure the barrel has enough clearance. It almost sounds like the action is settling as you fire. Perhaps the recoil lug isn't all the way against the recoil lug area in the stock. When tightening the action in the stock make sure the recoil lug is seated firmly against the area in the stock for it. When I tighten mine, I put the screws in loosely the stand the gun up on the recoil pad to make sure the action is all the way to the rear. I snug down but not tighten the front screw first then I snug down the rear. Then I go back and tighten them all the way, again front to rear.
Dolomite
Re: 12bvss .308 not grouping
After looking it over it seems the tang is tight in the stock.
Also i had to repair the wood around the front pillar where it split out and then bedded the front only area only.
Going to take it apart and give the tang some clearance and recheck and maybe bed it all.
As far as the bipod thats how it has pretty much always been shot and would print some nice groups,but that might have changed with the stock issues.
Now if i could just find a dang allen wrench,looks like i'm gonna have to buy a bunch since i keep loosing them.
Re: 12bvss .308 not grouping
Ok i got the rifle apart and added clearance all around the tang area,I was suprised to see how much i had to remove to get a small gap around all sides of it it was even worse on the bolthandle side it was really tight.
Soon as it stops raining here i'll have to get out and test it out again.