@longrange13, I’ve chopped a handful of barrels using just a hacksaw and a facing/crowning tool to square up the muzzle. All remained very consistent in accuracy except one.
The ‘one’ is a factory cz 527 varmint chambered in 223. Started out at 24” shooting a ragged hole at 100 yards off bench and bags. Shortened it up to 20” and opened up to 3” groups, shortened to 19.5” and shot 2”. At 19” it went back to 3”. At 18” I’m back to 2”. Barrel is now sits at 17.5” and I’ll give you an update as soon as I have one.
My best guess is the barrel some way, some how, has a loose spot in the bore that I’ll hopefully be able to cut out before getting to 16”.