A spotting rifle barrel is aligned and retained relative to a launch tube and a spotting rifle receiver housing. A first annular lug is coupled to an outer portion of a breech end of the spotting rifle barrel. A second annular lug is coupled to an inner portion of the spotting rifle receiver housing. The spotting rifle barrel extends through the second annular lug so that a forward end of the first annular lug abuts an aft end of the second annular lug. The forward end of the first annular lug and the aft end of the second annular lug meet at a complementary radius of curvature. The first annular lug is retained in an abutting relationship with the second annular lug. A boresight adjustment assembly cooperates with a muzzle end of the spotting rifle barrel to adjust the boresight of the spotting rifle barrel while allowing for axial movement of the barrel.