Update! I finally pulled this poor-shooting rig out of the back of the safe, determined to find a way to get it to shoot. After reading a tip on another forum, I removed the scope, as well as the weaver base. Under the base, I found a layer of goop that I can only assume was applied to make mounting the base easier durning manufacture.
After scrubbing it all off with a wire brush and solvent, I re-mounted the base, careful to tighten each screw no more than half a turn each,alternating until they were snug. I then torqued them down to 45 inch pounds using the same method, with a drop of blue lock-tight each.
I did the same with the Nikon scope , sans lock tight. After a good copper-removing cleaning, I headed back to the range. With the rest just ahead of the trigger guard, I settled in. Once I was on paper, I fiddled until I had a good POI and let it cool. The next three shots went into a .75" group.
I could not believe it! I let it cool again, ran a bore brush through it, and put another three rounds under an inch. Any flyers over the next 20 rounds were due to the poor trigger and my poor shooting. None of the 6"+ vertical stringing that relegated this rig to the back of the safe. I am blown away that the fix was this easy.
Apparently, that sticky goop coupled with uneven torque on that weaver base was sufficient to have some movement when the gun heated up. With solid mating surfaces and even torque, I am hopeful my wandering POI issues have been resolved. Sure looks that way!
My son is thrilled to be using it for whitetail this year. He took his first deer with it, but later missed an easy shot on a pig. I put it away until figuring this out, so now he can't wait to use it again.
Incidentally, it has a strong preference for Remmy Corlokt 100 gr rounds.
