Mine started life as a .300 whisper on a CZ mini Mauser LH action. It sports a 1:8 Lothar Walter barrel at 16. The issue with the Whisper was reliable extraction. It took a bit of tinkering to get the 221 fb brass to eject sometimes.
A couple of years later I sent the barrel out to Selph Arms to have the Whisper punched out to .300 Blackout. The rifle shoots like a dandy with both 220 subs, and 125 Noslers. The poi shift from super to sub is about 8.5 inches at 100 for me. Accuracy is good. Fun rifle to shoot and hunt with. There are tons of options now for a build, And brass is a non issue now.
I also built an AR built with 8 twist barrel at 16.
I am happy with my accuracy with subs.
A great caliber if you are going to suppress it.