I'm working on developing loads for a new 300 WSM. I've noticed that the majority of the groups are strung out horizontally. I've had some groups that went 3 inches horizonatlly and 1/2 inch vertically. This doesn't happen with every group, but I did notice a pattern. Even some of the better groups have more horizontal variation than vertical. These are generally 4 or 5 shots groups letting the barrel cool after 2 or 3 shots.

The barrel is free floated and I tried adding a pressure pad. This improved some groups but the same horizontal patterns were evident. I've done all the obvious stuff like checking the screws etc. Is there anything that might cause what I am seeing? Suggestions?

Thanks
Jeff

Horizontal stringing can also be a scope problem, either with the scope itself or it's mounting. With everything else you've covered, that would be the next place to look. I've got a pretty good feeling that it's going to be something with your optics.

Regards,
Tom

Agree completely with Kingfisher. As a matter of fact that's the first place I would have looked. There are far more optic problems than anyone realizes. Put a know good scope on there to eliminate that possibility. I've returned scopes to all the top domestic manufacturers at one time or another for these types of problems and invariably that fixes it.

Wind gusts will do it also.

WC

JAB,

I assume this is a sporter weight rifle? I have witnesses several of my customers bring sporter rifles that I built for them back to me that had similiar problems. First thing I do is take them out to my range and have them shoot in front of me so I can see how they shoot.

More times then not they are not using proper shooting technique and are allowing either the skinny forend or the rear of the rifle to wallow around in bags that are to large.

In every instance, switching their bags that do not fit the sporter style rifle stocks brings groups well under the moa level. So first off, make sure your shooting position is rock solid. This is critical with sporter rifles, they tend to be the most difficult to shoot off the bench because the design of the stock is simply horrible for this type of testing.

Please do not take my advice as a slam to your marksmenship as several of my customers could outshoot me in field conditions, they just needed a few pointers from the bench.

From there I would look at the bedding of your rifle. I have found that horizontal stringing is generally caused by a loose fitting rear receiver tang. Modern Winchester and Browning bolt actions with wood stocks are now bedded arounf the recoil lug but seldom are they bedded at the rear of the action. This can also create the symptoms you are relating.

These two factors I would say result in 75-80% of the horizontal stringing. THe optical set up as mentioned can also cause some interesting problems from time to time.

My question is what make of rifle do you have and what is the stock made out of. If it is one of the injection molded stocks, you may be better of replacing the stock with a quality synthetic or laminate, whichever you prefer with a quality bedding job.

Good Shooting!!!

50

Some good advice above.

Check the action screws to see if they are loose.

I had the same problem on my 300WSM, the loose screw was behind the trigger though. Watch the crosshairs of the scope while mixing a dummy round ( no primer or powder ) in with live ammo. The info may surprise you.

Travis F.

50,

Yes, it is a sporter weight...light sporter...is's a Kimber 8400. I checked the bedding and it looks very well done. There are pillars for both the front and rear screws. I will check the rear screw and make sure that nothing is slipping there. From memory it has a releatively flat surface. All the action screws have been tight when shooting.

I've shot off the bench with either a bull bad or a benchmaster. I've had very good groups using both these setups with other rifles (338Win) so I don't think the bench technique is the problem...no offense taken.

I'll also try another scope, but I don't think that's it. This scoped was pulled off another rifle and didn't have this problem before.

From everything I can see the gun is extremely well made. It's been a little perplexing to say the least. If I figure it out I'll be sure and post the solution.

Thanks

Jab, I recently had the same problem with my 300WM, I actualy created the problem by over tightening the action screws. I had no idea how important the proper torque was until I over tightened mine. I have read quite a few times on a number of boards that many people use the torque recomended by Winchester, 60in/lbs. This caused horizontal stringing and totaly screwed up the accuracy of my rifle. I found afterward by backing my tang screw off to about 20-25 in/lbs and the front screw to 30-35 in/lbs then tweeking them I was able to return the accuracy to my rifle. Just another thing to check out good luck!