Help Sighting In

[Limbic]

I had my guns pretty well sighted in at 300 yards. 7mm and 260 both with Rem700 actions. I went out and shot at 600. Found that the windage was anywhere from .5 to 1 MOA off to the right. There was zero wind blowing. I went back to 300 yards and found that both guns were now .5MOA to 1 MOA off to the left. So it seems that both guns shoot to the right, which I find kinda strange. Sounds like a shooter problem and not a gun problem.

Is this common? What are some of the causes? I'd think that the cross hairs are aligned correctly.

 

[kiwi3006]

Did you adjust the windage after shooting at 600 to make it shoot to the left at 300Yd?

Might be a couple of things, scope not aligned properly with the bore, check rings, bases and screw holes in action.

Might possibly be spin drift, but probably not 1 MOA at 600 yds. The JBM website now has a feature where you can calculate the spindrift for your load. There is a small checkbox at the bottom of the page.

Your scope might be canted slighlty, causing impact to move sideways as you increase elevation.

Hope thee ideas help.

Stu.

 

[canderson]

Sounds like a canting problem to me. Either the scope is not setup in line with the bore or you are canting the rifle. I believe that there is an article on reticle perpendicurality on this site. Just my two cents.​

 

[Chief1942]

Had a similar problem 2 days ago. I had my 7mm RemMag sighted in at 100 yds using Federal 175gr soft points. Went to the range to dial it in and develop my drop charts with what I want to use as my LRH round, HSM's 168gr Berger VLD load. Set the target at a ranged distance of 100yds. First shot wasn't even on the paper. Thought maybe it was due to the cold barrel. Fired several more and it was all over the map, high left , way right, way low right, etc. We're talking 8 to 10 inch spreads at 100 yds. Wasn't sure what was going on as I had it well dialed in with the other loads and really only expected the 168 VLD's to be somewhat higher only. Tried some of the 175 gr again thinking I may have gotten a bad lot of HSM ammo. They were not nearly on either. Checked for scope loosness and all the other things, ie. stock to action screws, etc. Nothing.

Packed it in and when I got home I removed the stock from the action and gave everything a close scrutiny. Couldn't see anything that looked like the culprit. Removed the scope from the action mounts, rings stayed in place on the scope and low and behold I think I found it. Seems the through bolt in the rear ring was not set in the slot of the weaver ring base but in front of it. I made the correction and feel confident I found the source of the problem. Recoil on the magnums can be pretty severe and something like this will certainly cause such issues even though the scope felt like it was secure. I'll confirm in a couple of days that it was the problem when I can get back to the range.

If necessary, take it all apart and put it back making sure you get everything the way it should be. Means having to re-sight again but at least you know what you are starting with.. Its often the small things that bite us in the butt.