josebd -
A few years back Dad gave me a Savage .22-250. The thing shot great for several years but suddenly I couldn't hit a standing coyote at 100 yards. I'm not talking a near miss, either, but rather patterns measured in FEET!
Over a 1-1/2 year period I tried all the usual suspects: action screws, scope mounting screws, new scope, another new scope, ad nauseum. Finally I discovered that after a very thorough cleaning with copper remover, the next trip to the range the group sizes would settle down as the barrel fouled, the rifle would shoot a few good groups, then return to shooting patterns. We're talking maybe 30 shots for the whole cycle, and that number was diminishing to under 20 by the end.
While still working with the rifle, my wife took pity and got me a new Ruger Varmint/Target in .22-250 for Christmas - so my immediate problem was solved. Eventually I came to the conclusion that the Savage barrel was the culprit. After investigating the expense of rebarreling, I decided to try selling the rifle (sans scope). A guy at a gun show wanted to rebarrel it and gave me $250. That and another $150 got me a like-new Ruger in .257 Roberts, with a Leupold 4x mounted.
Just a thought, maybe now is a good time to trade up to a newer rifle? Or two?
Good luck, I know how frustrating it can be.