While I may be new here to the forum I am not new to diagnosing problems with firearms. Are your groups concentric? or do they seem to be stringing? If so, are the strings running horizontal or vertical. Have you changed anything at all recently? When a problem like this happens to me and the fix isn't obvious, I always revert back to the basics.
Check the rings and base. All screws for tightness. Is the barrel of your rifle floated? If not has there been a weather change? Try a scope of known quality. Also, is the ammo that you have been shooting the same lot? This can truly effect your accuracy. Check the action screw for correct torque. My Shilen Barreled 10/22 likes to have a medium torque of around 15-20 inch pounds on it to shoot. When I tweak it just right it will consistently amaze me. Small group to date is a 5-shot, 50 yard group shot with an older lot of Fiocchi V-340. Center to Center .126".
Good Luck
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