M1A Horizontal Stringing

My M1A has suddenly began to string shots horizontally. I'm up to my ears in alligators at work right now so don't have time to do much diagnostics. Need some ideas to try when I have time. The rifle is a NM that was bedded and tuned by a former U.S.M.C. armourer friend in 2001 and since has always been very precise and consistant. Bedding job is getting old but still locks up tight. Has Leupold Mark 4 M1 scope in A.R.M.S. steel rings and an A.R.M.S. #18 mount. Everything seems tight as all witness marks line up still and I can't detect any movement. Missed a nice deer with it yesterday afternoon so I stot it once this am at 100 yards, P.O.I. was 10'' left of point of aim, elevation good. POI does'nt corrispond to the adjustments on the scope. To me it acts like the stock is contacting to barrel somewhere but right now I don't have the time to do a teardown to see. All thoughts and ideas appreciated, VH BTW, the ammo I'm shooting is Remington 150gr Corelokts. A neighbor gave me a 200 rd sealed case of it 5-6 years ago so it's all from the same lot.

Without getting too technical, I think that as the rifle warms up and things expand it's climbing in it's bed. Or do you think it's just jumping with the lash because of contact? If it is, you don't really have any way to find it except to look for rub marks.

Dead scope? I have had it happen.

I forgot about that...but I should think that with the top handguard removed you should still be able to do the dollar bill test under the barrel. Worst case you have to remove the op rod. That should tell if it's tight there or not.

A defective scope maybe, hasn't been used enough to be dead yet. I put the Mark 4 on in June 2009 and zeroed it then it sat in the closet until last deer season during which time I shot it a grand total of 4 times plus one more this year. Including those used for zeroing the rifle has been fired 10 times since the new scope was put on and before the POI shifted. I did a complete tear down last night and nothing's touching the barrel anywhere, the barrel channel has been opened up enough that it would be near impossible for it to touch the barrel under normal circumstances. Maybe just a new scope with sticky adjustments that needs breaking in? What ya think?

The last time I had this it wasn't on a Garand. However, it turned out my rear sight had loosened up and was walking laterally. Consider your scope mount.

Bob

VH, 10" at 100? That is more than a bad mount, barrel contact or bedding issue. I suspect the scope was banged, bumped or even had a degree of pressure applied to the scope while in the safe or case over a long period of time. Bad scope, highly unlikely.

I have pulled my SA M1A from the safe only to find it way the hell out even though I know nothing has ever changed. I attribute it to sun spots ;) Kind of like when I lose cellular service :banghead:

I have had three high dollar scope fail on me. All failed some place under 15 shots. Try another scope that will at least eliminate that part and check the mount.

I don't know what your real scope setup is, but if possible I would take the scope off and try to zero rifle with iron sights if you have them on the rifle. Obviously, this would only work if you have the irons in place and you had a zero on them before you mounted the scope. something very dramatic happened to put you 10" of your scope zero. Rick

Hey guys, been rather hectic around here the last couple weeks keeping 80 some odd pieces of cotton handling equiptment going that are scattered over 7 or 8 counties. Not much time left over for tinkering but I did get around to looking over the scope mount, nothing out of place or any wear detected. Probably gonna be a while before I get to do any shooting, or deer hunting:ugh::crying:, but I'll keep you posted. Thanks for the replies, VH.