The weapon (10) includes a barrel (13) joined to a barrel yoke (21) in a receiver (14) aft of a front housing assembly (15). The recoil system includes a main recoil spring (30), a secondary spring (23), a buffer group including rods (60), springs (61) and plate (63). A slide bolt assembly (40) includes a slide (41), a bolt (42), a face (43), bolt face levers (44) and actuating pins (45), all within the receiver (50). The bolt face (43) is driven vertically by the bolt face levers (44) to receive a new found round (91), load it and remove and discharge a spent casing (90). The slide bolt assembly (40) travels forward and aft during the firing cycle. On rearward travel it is accelerated rearward by accelerator (70) until reaching the buffer group and transfers its kinetic energy to the buffer group which in turn transfers that energy to the barrel (13) and the recoil spring (30) where it is absorbed without transferring the impact loading to the weapon mount (11).