Vertical stringing causes?

What causes vertical stringing?

I have a new Encore 7mm-08 that is showing a distinct tendency to vertically string its shots.

I took great care to brake-in the barrel, the scope base and rings are snug and the bullets are seated .005-.010 off rifling.

What is odd is that almost always, two shots are either touching or are much less than an inch from each other and one of the shots in a 3 shot group is either WAY high or low? Shots are never drifting right or left.

Today, while trying two other loads, the point of impact unexpectedly shifted 3-4" high with no change being made to the scope.

The rifle does seem to me like it wants to shoot, since nearly always two shots are either touching or are much less than an inch apart. The rifle is a Virgin Valley Encore with a Shilen 7mm-08 barrel.

I believe my trouble may be the scope, because the way the rifle is acting. The scope is a brand new Nikon Monarch.

What do you guys think? Could it be the scope is shifting? The gun really acts like it will group. I believe it is a scope problem. :

It happens to me when I don't allow the barrel to cool down.This sounds like your problem to me.Is the barrel clean?Most of my guns have to be cleaned every 15 to 20 shots because of copper buildup.Hope this helps!

Good evening Cal,

The stainless barrel on my rifle measures .800 diameter, I cleaned it before I took it to the range like I always do, so I know the barrel was/is not fouled.

Day One at the Range:
I shot very very slowly and cleaned after every shot for the first twenty rounds. Every group showed vertical stringing, no matter the load.

Today:
I shot two other loads and the rifle STILL displayed the exact same tendency to vertically string its shots. The thing that really got my attention was when one of the 3 shot groups unexpectedly shifted vertically 4-5"!

I really do think I may have a shifting reticle in my scope. I've done a lot of shooting in my time and I know its definitely not me when I'm shooting off the benchrest at 100yds.

Have you ever had a scope shift its point of impact like this one? I just don't believe its the rifle, because it often puts two shots touching or well under an inch.

There is no telling which of the three shots end up touching, but two are always close or even touching, with the other way up or down.

The load might be too hot.Have had this to happen.

Also have had mounts to get loose.Especially the bases.

I have a contender rifle and it shifted point of impact until I found a way to float the barrel or keep the barrel from touching the forearm.I put a tiny washer on the inside of the forearm on the bolt that held it on.I also had to change pivoting pins.This seem to help make it lock up the same each time.

The worse scenario,I traded a Sako off because it would not group and found it to be the scope.

Are you placing the forearm on the rest the same place each shot?This can effect the group.

I have not found any cut and dried solution.With me it has been a combination of several things.Do 1 at the time and shoot it if possible till you hit the problem.

The more I think about your problem the more it sounds like my lock up problem I mentioned.

One other thing,what is the twist of the barrel?A fast twist takes a heavy bullet and a slow twist a light bullet.None of my 1 in 12 or 1 in 14 rifles will shoot a heavy bullet.You might try different weight bullets.Hope some of this rambling helps.

I've been making sure to place the forearm on the same place on the bench.

The forearm has the hanger bar that floats it off the barrel. That was an option I went with at the suggestion of Virgin Valley.

I checked the action and it feels rock solid, as are all the base and ring screws.

I even changed primers, bullets and tried different overall lengths on the bullets. So far, the rifle STILL exhibits a distinct tendency to erractically shoot vertically strung groups-and shifting point of impact.

Maybe I'll try some factory loads to see how they'll shoot. My gut feeling and hope, tells me I have a scope problem. I know on a new scope that is doubtful, but I guess its possible. :

Lead check the crown for a burr.

DOUBLE check powder charge.

SHOOT it free recoil. Vertical stringing can be pulse related.

You might want to read this thread. It might have some information that could help.

http://www.bellmtcs.com/forum/index.php?act=ST&f=9&t=456&

Ronnie