Abstract: The joint construction comprises a coupling ring slidably received in a motor tube connected to the front end of the military rocket motor. The coupling ring is formed with longitudinal slots alternating with flexible fingers having locking projections engageable with a locking channel and an adjacent locking flange within the tube. An adapter ring is connected to the warhead by first screw threads and is adapted to be connected to the coupling ring by second screw threads including external threads on the adapter ring and internal threads in the coupling ring. The adapter ring has a reduced tapered end portion for receiving a wedging tapered expansion ring made of a eutectic metal alloy having a low melting point. As the second screw threads are engaged, the expansion ring flexes the fingers outwardly by a wedging action and causes the projections to interlock with the channel and the flange.