Well, I loaded up 20 for test tomorrow.
While chamber checking some brass and going over things I noticed the reason the loaded rounds had resistance was because primers weren't fully seated (cheap RCBS hand primer and new ADG brass), and also noticed my UM rings have scooted forward.. SO, reinstalled with a recoil pin, and torqued with an ugga from an M18 impact.. (kidding..).
So there's a couple tests going on now, going to check zero with 10. Half of which are loaded and pulled brass/bullets that had light resistance seating, half are new brass/new lot of bullet (visibly different colored tips) that took some force to seat. Other 10ish are to verify at long range with half the brass preloaded with the necks stretched, half new.
Last weekend this rifle and combo shot a .6" 10 shot group with an apparently moving optic. Feel free to post predictions on the result of this monstrosity of events..