Patent ID: 8397414

Claim:
A structural device installed into the longitudinal slot of an M4 type receiver extension prior to the installation of a telescoping carbine buttstock, said M4 type receiver extension comprising: A cylindrical body predominantly inline with a bore axis of a firearm and, A lower rectangular portion at a bottom center position of the cylindrical body with a longitudinal slot that contains a plurality of locking detent holes in the underside of it wherein said longitudinal slot is a known depth from the surface of the lower rectangular portion and the locking detent holes are a known depth from the surface of the longitudinal slot designed for the receiving of a telescoping buttstock's positional locking pin wherein the longitudinal slot allows the bin and buttstock to slide fore and aft and the locking detent holes arrest the buttstock via its positional locking pin in a desired position; Said structural device comprising a body with an upper portion of a cylindrical shape and a lower portion of a rectangular shape wherein the upper portion inserts axially into a locking detent hole and the lower portion occupies space between locking detent holes in the longitudinal slot of an M4 type receiver extension.