Your thoughts

[Coyoter]

A friend of my recently purchased a Winchester model 70 in 25 WSM. It's got a synthetic stock and is bedded only in the recoil lug area. He's getting shot strings that go high and right with each pull of the trigger (little time between shots, even though it's a light sporter bbl.) with the first shot on the $. He's tryed IMR 4831 and IMR 4350 with Rem 9 1/2M primers and Varget with CCI-BR2 primers. He's tried both 100gr Nosler PTs and BTs. He's also bought one of those rubber do-hickeys from Limb Saver that are supposed to be the latest version of the Boss, but he's only shot 6 rounds with that stuck on the bbl.
Does anyone have any ideas that will get rid of the stringing that doesen't include rebarreling to a Shilen match bbl?
Many thanks to responders and good hunting to all.
Coyoter

 

[EddieHarren]

I'd start buy checking to see if the forearm is putting pressure on the barrel.

 

[sniper2]

Also check tightness of rings,bases ect.

 

[Coyoter]

See, I knew I was forgetting something.
The barrel is freefloated, both before any shots are taken and after.
I'll certainly pass along to double check the mounts too.
Thanks,
Coyoter

 

[D.P.]

Coyoter
It could be a number of things, but I can tell you I was shooting a new win 25wssm the other day. Dont know the model Stealth? HS stock controlled push feed.
R-19
100NBT Jammed
BR 2's
Might just be the most accurate factory rifle I have ever shot.
after playing with Bergers and others two grouping the NBT's are insane. several 1/2" 200 yard groups one with low charge and one with high.

 

[Coyoter]

Ha! I'll pass that one along to him just to **** him off!
We both realize that we can't expect a light/hunting rifle to shoot tight groups off of a bench all day, but that the second shot strings off of the first and the third is worse yet is the major concern. The first shots (cold bbl.) probably hit under .5MOA. The big issue is trying to compensate for stringing and enviromental conditions at the same time if the first shot isn't quite where he wants it.
Coyoter

 

[Fiftydriver]

In general, horizontal stringing is caused by bore bedding and vertical stringing is caused by bolt lugs that are not fully in contact.

Now this is in general as a stock hitting a barrel can do many strange things.

That said, if the rifle shoots well with lower pressure loads but gets fliers when the pressures increase, more then likely its a bolt lug issue. At lower pressures one lug can support the round, as the bolt thrust increases with the increased load, so does the flex in the bolt and generally you will see vertical stringing.

Pull the bolt, and look at the contact areas and see if they are both contacting the receiver. If this is a new rifle this may be difficult to tell for sure but you can generally tell if you have a floating lug.

The cure???? If it is close, lapping it in will do most of the time, if it is floating a significant amount, the only correct fix is to pull the barrel and square up the receiver. It will also require the barrel to be set back slightly to set the headspace back to where it should be.

Check the stock and mounting hardware first. Then look at the bolt lugs to make sure they are making even contact.

If they are all checking out, them check to make sure the receiver screws are not TOO tight. This can flex the receiver in an HS stock and cause fliers as well. A simple stress free skim bedding will cure this if it is the problem.

I have yet to see any HS stock that did not perform better after being skim bedded then before it was bedded. At least accuracy never has decreased after skim bedding.

Just a couple more things to check on.


Other then that, you may have a barrel with a stress in it that rears its head when the barrel warms up!!

Good Shooting!!

Kirby Allen(50)

 

[davewilson]

if the lugs are both touching i would consider getting a cryo treatment. production barrels can be very "stressed"

 

[Coyoter]

Thanks everyone.
I've passed along all the great info I've gotten and I'm leaning towards the "lugs need lapping" solution. Not having looked at it myself mind you. He backed the charges down toward the minimum and the groups rounded out. Then he adjusted the Limb Saver down the barrel in 1/4" increments for a little over an inch. Now he's getting round groups that are under .5MOA. The velocities are what you'd expect from a .257 Roberts, but they're on target and he's happy.
We'll probably play with it some more come spring.
Don't I remember reading that the proper way to tighten an action into a stock is to crank the forward screw down really tight and the one on the trigger guard just untill it snugs up?
Thanks,
Coyoter