7600 impact shifts

[vinconco]

I have a 7600 carbine in 30--06 and am having trouble with impact shifts.  I can zero the rifle and get a fairly good group and then the impact shifts 2 or 3 inches.  I had a Leupold 1 x 4 shotgun scope on it and changed it out with a new Bushnell elite 3200 3 x 9 and am still having the same problem.   I am using Burris Signature turn in base / rings.  I cleaned the threads and used red loctite on the base so I don't think the mounts are the issue.   I have an old 760 with the same mounts and a Bushnell Elite 4200 2.5 x 10 that hold zero perfectly.  I heard something about loose barrels but can't find the thread anymore so does anyone have any ideas?

Thanks

Steve

[Siskiyou]

Could copper fouling be causing your problem?
 

[vinconco]

Could copper fouling be causing your problem?
 

Copper sure can cause problems but I always remove the copper at each cleaning so I don't think that could be it.  These 760's seem to accumulate their share of it too …and fast.

[jpsmith1]

I'm the loose barrel guy, I think.  My .243 Win 7600 had the barrel go loose the first day I carried it in the field.  I was 13 or 14 and fell, banging the gun on a log.  The next day at the range, it shot a lot of wandery , shifty groups.  The gunsmith tightened the rod under the slide.  That cured the problem forever.  You could probably do it yourself with a bit of rod to spin the tube. 

Look real close and you'll see it.

[vinconco]

Thanks for the loose rod tip, I'll check it out this weekend.