Can confirm. Three guns. No such issue. Swap back-and-forth without problem and zero degradation in accuracy.
Neat. Maybe its barrel dependent. Tested this across barnes, hornady, and Lehigh bullets with major POI and accuracy shifts (oddly left to right shifts as well).
FWIW I shoot suppressed so the additional backpressure may impact
3 of 4 were semis with chrome lined barrels. Bolt is a stainless.
I doubted this the first time I'd seen mention of it, as someone who only cleans my guns when the groups open up. But this issues been plaguing me for a while. Even had a rifle rebarrelled because when I switched to barnes my 100yd POI shift was 7 inches right and 2 Low. Enough proof sent alongside that PWS warrantied. New one wasn't as bad but had the same issues. Finally resolved to just believe my guns don't like barnes.
But saw a video from Ron Spomer mentioning it and he's not known to buy into fudd lore. So I did my own testing at the range. Shooting 40 rounds of ball ammo ensuring 0. Swapping to various coppers and can't get them to shoot well. Swapping back to ball and their accuracy dramatically affected.
Scrub to bare metal. Ball shot great for 100 rounds. Scrubbed to bare metal. Coppers shot good (only did 40 rounds each brand before rescrub for cost reasons)
One exception was my CX in one of my 223s did shoot well. And the 150gr barnes did fine in the boltie.
A little over a thousand dollars of ammo and a few bags of pouches later. I'm convinced that something, maybe the mixing of the different alloys, does cause some problems.
Anecdotally my father reports no issue from his 6.5 grendel but also doesn't swap ammo types as often as I do (I use my rifles for more than hunting).
Do what you will with the info ¯\_(ツ)_/¯. All my guns like CX and TTSXs now suddenly