As well as in shorter barrel lengths (~8″) the 300BLK is much outstanding for supersonics, at the very least. Long barrel 300BLK is near pointless IMO, you can find other rounds that outperform it handily in the exact same System, with identical length barrels. Of importance, the non-adjustable fuel block https://300blackoutcases31841.blogocial.com/300-blackout-brass-things-to-know-before-you-buy-74346125