While I was sighting in my new .300 WSM Winchester Model 70 yesterday, I had something happen that I haven't had before.

I was taking a lot of time between shots, and cleaning after each one and letting it cool. when I finally got it where I wanted it, I went ahead and fired a 3 shot group. It strung the 3 shots out righht to left. 1st shot right no the money, 2nd shot about 1 inch left, 3rd shot about 3/4" left. I let the gun cool down and cleaned it again. Fired second group, smae exact thing. My vertical point of impact is staying right whre I want it, but it's stringing right to left.

The gun is a Model 70 Laminate Stock .300WSM shooting 180 Grain Winchester Factory Ammo (Plain Silver Box)

Any ideas or potential fixes ?

most people that shoot comp. shoot a few fouling shots, read this post maybe it will help, myself after i do a thorough cleaning i fire 3 throw away shots. hope this helps some.


http://forum.hunting.net/asppg/tm.asp?m=809438

I definately agree that you need to use up to 3 fouling shots. If however this does not completely clear up the problem (I'm suspicious of the horizontal pattern) then you may have a problem with the barrel itself having some internal stresses that are showing up as the barrel is heated. This can be corrected with cryo-freezing. See this link: http://www.diversifiedcryogenics.com/gunbarrels.htm

Here's a quote from that site:

Edit: If I recall correctly, Gander Mountain offers this cryogenic service as well.

I agree with the cryo suggestion.

I know two guys that did it with their shotguns and it really helped.

Also just check to see if the barrel hits the stock. (floating) I had a 7mm that was throwing bullets also. When the barrel was floated (buy me with a dremill tool and yes it was a "hack job" but I digress) It then shot very well. It seemed to throw them on shots 4 & 5 for me.

Sounds like you may have a problem with the bedding of your rifle. But first you could try a different type of ammo to see if it makes a difference. If you are using your rifle for hunting then most first hunting shots are shot from a clean cold barrel so thats how you want to know your bullet react. Fouling shots are used on the range for competion shooting but seldom are they used before hunting as this could require leaving your rifle dirty for days on end or firing a couple of shots each morning.

Best Wishes

Agreed, sounds like you have a bedding problem. Try some different ammo, but I suspect you'll find similar results as the barrel warms up. You'll have two options -
call Winchester, and maybe send the rifle back for correction, or glass bed the action, and free float the barrel.