my problem was
I have a 222 rem. Tack driver for 10 years as I reload, Took it out and was all over just like you are. Just as someone else said, Check all the screws. The front screw that holds stock to the rifle came loose, Tightened it and right back to being a tack driver. Ez to check. It takes some time to figure it out but if all screws are tight and the stock is not touching the barrel somewhere like my rem 700 308 was. I would guess scope or mounts or both. I also only use one brand of ammo and each rifleing twist likes a different weight of bullet. like fast twist likes heavy bullets slow twist likes light bullets so if you have a 1 in 9,10, 11 or 12 twist it will shoot heavy bullets better than light ones.
Good luck, Stan