Abstract: An AR-pattern firearm comprises an upper receiver, a housing positioned above the upper receiver and containing a recoil spring assembly, a bolt carrier assembly positioned in the upper receiver, and a bridge plate operably connecting the bolt carrier assembly to the recoil spring assembly. Discharge of the firearm causes rearward movement of the bolt carrier assembly out of battery and hence rearward movement of the bridge plate which stores energy in the recoil spring assembly, whereupon the stored energy in the recoil spring assembly causes the bolt carrier assembly to move forward back into battery.