Patent ID: 8573126

Claim:
A cartridge for ammunition comprising: a base having an axial end section having a primer cavity therein and a radially outwardly extending peripheral extraction lip; an annular wall extending from said enlarged outer peripheral lip section to an opposite end; an annular ledge axially positioned at an inner end of said primer cavity and radially extending inwardly from said annular wall; a passage having a reduced diameter compared to said primer cavity and extending through said annular ledge; a main charge cavity at an opposite side of said ledge from said primer cavity and within the confines of the annular wall; a knurl section on an outer surface of said annular wall; said knurl section having canted grooves thereon; and a plastic cartridge case having a rear end comprising: an outer flange extending about said annular wall and engaging said knurl section, and an inner flange extending about said main charge cavity inside said annular wall and overlay an entirety of said annular ledge only to said passage, wherein said annular wall is sandwiched between said inner and outer flanges with said knurl section engaging said outer flange, and wherein said knurled section forms a raised pattern extending outward from said outer surface of said annular wall from 0.004 to 0.010 inches.