Horizontal stringing?

[finnwerke757]

Im shooting a Creedmoor, and with 140 SST's I get great vertical like 1/2", but the horizontal goes to like 1.5" what the hell is goin on? Other loads it either likes or hates. But this bullet I get horizontal stringing. Thanks in advance.

 

[K22]

First I'd check my shooting technique and rule it out as a possible cause. I assume you already check the mounts, rings, and bedding screws for tightness. I assume the scope was mounted properly square to the rifle, i.e. not canted.

If possible, have someone observe you while you shoot to see if you're canting the rifle left or right. Is your thumb too far over the pistol grip causing the rifle to torque to one side under recoil?

If you're shooting off the bench - try holding the stock under the forearm instead of letting the rifle "free recoil" and see if that eliminates the problem.

Next I put another scope on the rifle, one you know is reliable, and test for stringing. I recently had a high quality Nikon scope that I used for years go bad on me. It does happen.

Next, I start experimenting with different load combinations. I had one rifle that would vertical string with a certain combination. Don't ignore the primer either - sometime a change in primer will eliminate horizontal stringing. Obviously this option is more tedious and costly but you may have to try it. Just change one component at a time and see what happens.

 

[finnwerke757]

Im kinda ruling out the technique, because I can shoot other loads well just this one is stringing.

 

[JohnMill]

757,
Just a possible; When I was shooting 6PPC I would start low and add powder until I got rid of the vertical. If I added powder after the vert disappeared it would start to string horizontal. I could then return to the last no vert load and have confidence that I was at the maximum usable load. I'm not sure now that it was always true but it served me well.

John