As well as in shorter barrel lengths (~8″) the 300BLK is much exceptional for supersonics, no less than. Extensive barrel 300BLK is near pointless IMO, you could find other rounds that outperform it handily in the identical platform, with very same size barrels. You will need to tweak subsonic handloads https://stephenhmtyc.blazingblog.com/39104664/the-best-side-of-300-blackout-brass