A firearm in the nature of a rifle with a plurality of exchangeable barrels, any one barrel being adapted to be threadedly connected to the receiver of the action. Thus, barrel replacement is accomplished by retraction of a set screw and unthreading of one barrel from the receiver and, thereafter, threading of a second barrel in its place and tightening of the set screw, once proper receiver-barrel alignment is achieved. Barrel exchange is accommodated by a depressible stock insert which yields to dimensional variations of each barrel during barrel removal and replacement. A wrench-receiving counterbore at the distal end of each barrel permits suitable tightening of each barrel prior to firing. Barrel alignment is achieved by use of alignment markings on the distal end of the receiver and the proximal end of each barrel.