Greetings @ifonlypn,
As others have said the problem is with the reloads. I would stick with one projectile until you get the problem sorted. You said you have fired Sako and Norma cartridges so presumably have the cases so you could test some loads in one of those. If they still shoot like shit then it is likely not the Winchester cases. Next I would try a different powder. I have been testing some .222 loads with BM8208 in Sako brass and 55 grain projectiles and it shot like your Sako ammo. BM2 should also be great as previously mentioned. You are using two types of primers so pick one and stick with it. The key to trouble shooting is to change one thing at a time. I have assumed that you did not full length size your new brass before loading, this can result in poor accuracy until fire formed. From here it is down to loading technique. See if you can get a local handloader with plenty of experience to look over your processes and would likely would have some simple suggestions that you won't get from a forum.
Regards Grandpamac.
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