WARNING - 300BLK 147gr Subsonic velocity problems
This video investigates significant velocity variations in 300 Blackout subsonic loads, specifically 147gr with Accurate 1680 powder. The presenter replicates a commenter's findings where powder position within the case dramatically affects muzzle velocity, with swings up to 200 ft/s observed. This phenomenon is linked to inconsistent ignition, particularly in low-charge-weight, high-capacity cartridges. The testing involved comparing CCI BR4, SNB, and Federal AR Small Rifle Match primers, shooting rounds with powder settled horizontally versus vertically (powder towards the primer).












