A schematic from the Heckler & Koch roller-delayed blowback system The HK21 is often a selective fire roller-delayed blowback-operated firearm with a semi-rigid locking system intended to retard the rearward movement from the bolt. This delay was accomplished by artificially raising the inertia with the bolt by using an angular, https://togel-sgp80234.dsiblogger.com/55715973/a-review-of-hk