A projectile launch assembly includes a launch tube having distal and proximal ends and an inwardly extending dimple structure therebetween, the proximal end being configured to receive a firearm muzzle, a receiver disposed on the distal end of the launch tube and having connector structure at a distal end thereof for connection to a projectile, an energy absorbing plug disposed in the launch tube and having a proximal end portion adjacent the dimple and a body portion extending distally, and an energy transfer piston disposed in the launch tube and having a proximal end configured complementarily to the plug and having a distal end configured complementarily to a proximal end of the receiver. A bullet leaving the firearm muzzle is absorbed by the plug which is thereby moved with the piston distally in the tube, the piston engaging the receiver to propel the launch assembly and projectile from the firearm muzzle.