Remington UMC Ammunition 300 AAC Blackout Subsonic 220 Grain Open-Tip Flat Base (20pk)Designed from the ground up to provide quiet, reliable performance, this round is perfect for AR 15s chambered in 300 AAC Blackout. The bullet was created specifically for the 300 AAC Blackout, combining the popular 220 grain, open tip design with a new, flat base. A cannelure ensures consistent loaded length and allows the brass crimp to hold the bullet firmly in place, eliminating the possibility of bullet setback. The powder load was developed to