Reduced energy MSR system
A system for firing reduced energy cartridges from a modern sporting rifle utilizes a bolt assembly weighing less than a conventional bolt assembly for such rifles and utilizes blow back for cycling the bolt assembly rather than gas operation. A bolt insert in a polymer bolt carrier of the bolt assembly has a projection that fits within a recess on the rear face of reduced energy cartridges. The reduced energy cartridges having a polymer casing, a rimfire power load for propellant, the power load recessed from the rear face of the casing. The power load seats in in the casing surrounded by a reinforcement liner embedded in the polymer casing.
1. A reduced energy cartridge, comprising:
a polymer case having a polymer case wall, the polymer case including:
a generally cylindrical body portion defining a first outer diameter about a longitudinal axis, the body portion including a base portion defining a base lumen;
a neck portion defining a second outer diameter about the longitudinal axis that is less than the first outer diameter, the neck portion defining a neck lumen; and
a tapered portion extending between the body portion and the neck portion;
a projectile including a first portion disposed within the neck lumen and a second portion extending forwardly beyond the polymer case;
a reinforcement liner including a sleeve portion, a shoulder portion, and a flange portion, wherein:
the sleeve portion defines one of a right-cylindrical geometry and a tapered-cylindrical geometry from a proximal end of the sleeve portion to a distal end of the sleeve portion, the sleeve portion being disposed at least partially within the base lumen and defining a sleeve lumen that is substantially concentric about the longitudinal axis,
the shoulder portion extends radially outward from the proximal end of the sleeve portion and defines a radiused inner surface, and
the flange portion extends from a proximal end of the shoulder portion and extends radially outward and beyond the shoulder portion and extends rearwardly beyond the base portion of the polymer case, the flange portion defining a minimum inner diameter that is the same as an inner diameter of the proximal end of the shoulder portion; and
a propellant unit disposed within the sleeve lumen, the propellant unit including:
a housing including a body portion and a hollow rim portion that cooperate to define a cavity, the hollow rim portion being registered against the radiused inner surface of the shoulder portion of the reinforcement liner;
a propellant charge disposed inside the cavity for producing a quantity of propellant gas; and
a priming material disposed inside the hollow rim portion for igniting the propellant charge,
wherein the propellant unit and reinforcement liner cooperate to define a recess at a proximal end of the reduced energy cartridge,
wherein the reduced energy cartridge is a rim fire cartridge.
2. The reduced energy cartridge of claim 1 , wherein the sleeve portion of the reinforcement liner includes a radial projection that projects radially outward and is imbedded within the polymer case wall of the body portion.
3. The reduced energy cartridge of claim 2 , wherein the radial projection is disposed at a distal end of the sleeve portion of the reinforcement liner.
4. The reduced energy cartridge of claim 3 , wherein the radial projection is continuous.
5. The reduced energy cartridge of claim 3 , wherein the radial projection is a flared portion.
6. The reduced energy cartridge of claim 1 , wherein the polymer case is an injection molded case that is overmolded onto the reinforcement liner and the projectile.
7. The reduced energy cartridge of claim 1 , wherein an outer surface of the sleeve portion of the reinforcement liner includes texturing for enhanced coupling between the polymer case and the reinforcement liner.
8. The reduced energy cartridge of claim 1 , wherein:
the polymer case defines a body lumen between the base lumen and the neck lumen, the body lumen having a diameter that is less than a diameter of the base lumen; and
the polymer case wall is unitary from the body lumen to the first outer diameter.
9. The reduced energy cartridge of claim 1 , wherein the propellant unit is a rim fire blank.
10. The reduced energy cartridge of claim 1 , wherein the propellant charge is sized to fire the projectile at a velocity of less than 1125 feet per second.
11. The reduced energy cartridge of claim 1 , wherein the recess defines an axial dimension in a range of 0.02 inches to 0.07 inches inclusive.
12. The reduced energy cartridge of claim 1 , wherein a proximal end of the projectile is registered against an annular ring that extends radially inward relative to the neck lumen.
13. A reduced energy cartridge, comprising:
a polymer case having a polymer case wall, the polymer case including:
a generally cylindrical body portion defining a first outer diameter about a longitudinal axis, the body portion including a base portion defining a base lumen;
a neck portion defining a second outer diameter about the longitudinal axis that is less than the first outer diameter, the neck portion defining a neck lumen; and
a tapered portion extending between the body portion and the neck portion;
a projectile including a first portion disposed within the neck lumen and a second portion extending forwardly beyond the neck portion of the polymer case;
an external reinforcement sleeve including a sleeve portion, a shoulder portion, a neck portion, and a flange portion, wherein:
the sleeve portion defines one of a right-cylindrical geometry and a tapered-cylindrical geometry from a proximal end of the sleeve portion to a distal end of the sleeve portion, the sleeve portion surrounding the base portion and being substantially concentric about the longitudinal axis,
the shoulder portion extends radially inward from the proximal end of the sleeve portion, and
the neck portion extends proximally from the shoulder portion, and
the flange portion extends from a proximal end of the neck portion and extends radially outward and extends rearwardly beyond the base portion of the polymer case, the flange portion and the neck portion defining a minimum inner diameter of the external reinforcement sleeve; and
a propellant unit disposed within the base lumen, the propellant unit including:
a housing including a body portion and a hollow rim portion that cooperate to define a cavity, the hollow rim portion being registered against the base portion of the polymer case;
a propellant charge disposed inside the cavity for producing a quantity of propellant gas; and
a priming material disposed inside the hollow rim portion for igniting the propellant charge,
wherein the propellant unit and the external reinforcement sleeve cooperate to define a recess at a proximal end of the reduced energy cartridge.
14. The reduced energy cartridge of claim 13 , wherein a proximal end of the base defines a radiused inner surface that surrounds the base lumen, the hollow rim portion of the propellant unit being seated within the radiused inner surface.
15. The reduced energy cartridge of claim 13 , wherein the external reinforcement sleeve includes a retention feature that extends radially inward and into the polymer case from an inner surface of the external reinforcement sleeve.
16. The reduced energy cartridge of claim 15 , wherein the retention feature is a punched retention feature.
17. The reduced energy cartridge of claim 15 , wherein the retention feature is a plurality of dimples.
18. The reduced energy cartridge of claim 15 , wherein the retention feature is at least one annular protruding ring.
19. The reduced energy cartridge of claim 15 , wherein the retention feature is a plurality of through-apertures that pass through a thickness of the sleeve portion.
20. The reduced energy cartridge of claim 15 , wherein the retention feature is a radial protrusion that extends from a distal end of the sleeve portion.