Shellcase for controlling reflections of primer shockwaves

A shellcase body for use as part of an ammunition cartridge, comprising:

• an annular base portion having a center boring formed therethrough, having proximate thereto a point of origin from which primer explosion is initiated;
• a substantially cylindrical middle portion having a substantially straight sidewall including an aft end and a fore end, said aft end being joined with said annular base portion, said annular base portion and said substantially cylindrical middle portion being arranged around a center longitudinal axis;
• an annular shoulder portion having a semi-circular sidewall that extends between an aft end and a fore end, said semi-circular sidewall having a curvature that is defined by a circle having a predetermined radius and a center that is positioned a distance away from said center longitudinal axis, wherein said aft end is joined with said fore end of said substantially straight sidewall at a secant point of said circle;
• and
• a substantially cylindrical neck portion having a substantially straight sidewall including an aft end and a fore end, said aft end being joined with said fore end of said semi-circular sidewall, wherein said predetermined radius and center of said annular shoulder portion define an interior surface having an angular orientation relative to said point of origin that is effective for redirecting a substantial portion of all shock waves originating from said point of origin away from entry into said substantially cylindrical neck portion, to thereby reduce the risk of a projectile associated with said open end from becoming prematurely dislodged as a result of shockwaves.

An ammunition cartridge, comprising:

• a shellcase body including:
• an annular base portion having a center boring formed therethrough, having proximate thereto a point of origin from which primer explosion is initiated;
• a substantially cylindrical middle portion having a substantially straight sidewall including an aft end and a fore end, said aft end being joined with said annular base portion, said annular base portion and said substantially cylindrical middle portion being arranged around a center longitudinal axis, said substantially cylindrical middle portion having an internal cavity in communication with said annular base portion;
• an annular shoulder portion having a semi-circular sidewall that extends between an aft end and a fore end, said semi-circular sidewall having a curvature that is defined by a circle having a predetermined radius and a center that is positioned a distance away from said center longitudinal axis, wherein said aft end is joined with said fore end of said substantially straight sidewall at a secant point of said circle;
• and
• a substantially cylindrical neck portion having a substantially straight sidewall including an aft end and a fore end, said aft end being joined with said fore end of said semi-circular sidewall;
• a primer positioned within said center boring of said annular base portion;
• a propellant positioned within said internal cavity of said substantially cylindrical middle portion;
• and
• a projectile having fore and aft portions, at least a portion of said projectile positioned in and retained by said substantially cylindrical neck portion, said aft portion positioned adjacent said aft end of said substantially cylindrical neck portion and said fore portion extending from said substantially cylindrical neck portion, wherein said predetermined radius and center of said annular shoulder portion define an interior surface having an angular orientation relative to said point of origin that is effective for redirecting a substantial portion of all shock waves originating from said point of origin away from entry into said substantially cylindrical neck portion, to thereby reduce the risk of said projectile becoming prematurely dislodged as a result of shockwaves entering said cylindrical neck portion.