This ammunition is from the original ar15.com group buy. It uses the Nosler 77 grain OTM bullet that has a cannelure and is crimped in place. The primer pockets are sealed and crimped. This ammunition has a muzzle velocity of over 2800 fps from a Colt 20" barrel. This ammunition is loaded to NATO pressure and should only be used in a 5.56 or Wylde chamber.