I've got an older 12bvss in .308. Lately i been having problems getting it group well,I'll get 2 shots that touch then all of a sudden it will throw one or more rounds an inch or better away from previous shots.
This happens with quite a few different loads nothing as far as loads seem to make a difference. How much clearance is needed at the tang?
Also I have not swapped scopes yet but might get on that tomorrow if i can. I had to fix the front pillar area by bedding it.
An other suggestions as to where to look for problem areas this rifle has shot ragged one hole groups from time to time but now it is not consistant at all and it's starting to suck.
I've tried wc846,varget,ramshot tac and imr 4064 with 168 nosler custom comps. seated all the out to the lands back to 2.800" that the manual states.
One thing that was done was a brake was installed and the point of impact will change greatly when zero'd with it on then removing it. Could the brake disturb harmonics enough to where it is not going to group with it on? Also it does this off a bipod and rear bag and also off front and rear bags.
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?
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
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.
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.
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