I have a few of these rifles; They shoot sub-MOA when its sunny and warm, and then expand to 2-MOA plus when the temperature drops. My questions are:
1. What, if anything can be done to a rifle with this problem?
2. What can I do to avoid buying (both as a new or custom) one of these in the first place.
3. What may cause this problem?
Thanks for your help.

If they have wood stocks they probably are showing some change in the barrel channel(temporary warping) with changing moisture content. I had a Sako 222 that moved nearly 3/8" in the forearm with changes in humidity and put a LOT of pressure on one side of the barrel.The answer in that case was freefloating the barrel and then filling with enough glass plus a layer of cloth to stiffen the fore arm and prevent warping.

Jim

Old Fart-- (does that mean you're too diluted to stink?)

First off we need to figure out *why?*.

Have you tried altering the tang screw tension when the accuracy goes to pot? That would be the first thing to try.

Bedding is the problem........the answer lies in experimenting with it and laying voodoo curses on it.

Maybe you're shivering????

I have a Savage 110 with that same problem when I lived in Idaho. In summer time it would shoot .754 MOA and in the winter it would shoot 3 MOA. The stock would twist to the left in cold weather very noticably, so I re-stocked it with an MPI fiberglass stock and solved the problem.

I'll check the bedding. It is free-floated, but I have only checked it inside. Thanks for your help.
I'll keep you posted.
OldFart
("A lot of hot air, and none of it any good")