As well as in shorter barrel lengths (~8″) the 300BLK is much superior for supersonics, at least. Very long barrel 300BLK is near pointless IMO, you can find other rounds that outperform it handily in exactly the same System, with very same duration barrels. Castings are robotically or manually ground https://brass300blackout74116.blog2news.com/39387434/300-blackout-bullets-for-reloading-secrets