Reduced energy cartridge

• US 5,359,937 A
• Filed: 01/21/1992
• Issued: 11/01/1994
• Est. Priority Date: 03/22/1990
• Status: Expired due to Term

• Current Assignee: General Dynamics Ordnance and Tactical Systems - Canada, Inc. (General Dynamics Corporation)
• Original Assignee: SNC Industrial Technologies Incorporated /LES Technologies Industrielles SNC Incorporated
• Inventors: Dittrich, William A.
• Primary Examiner(s): TUDOR, HAROLD JAY
• Application Number:
  US07/773,591
• Time in Patent Office: 1,015 Days
• Field of Search: 102/430, 102/434, 102/439, 102/444, 102/445, 102/446, 102/447, 102/464, 102/520, 102/521, 102/522, 102/523, 102/530, 102/531, 102/532, 89/14.5
• US Class Current: 102/430
• CPC Class Codes: F42B 14/064 Sabots enclosing the rear end of a kinetic energy projectile, i.e. having a closed disk shaped obturator base and petals extending forward from said base
• CPC Class Codes: F42B 5/02 Cartridges, i.e. cases with charge and missile

Abstract

A cartridge 10 for low-mass, frangible projectiles 60 comprises a cartridgease 12 having a primer 14 at its base and a sabot 30 or piston 30 at its mouth. The piston 30 can be provided with longitudinal orifices 44, diagonal orifices, 44a, grooves 64 or any combination of orifices and grooves. The projectile 60 is inserted into a cylindrical recess 46 in the front portion of the sabot 30. The orifices 44 are in communication with this recess 46 to permit propellant gas to bleed through and accelerate the projectile 60 upon ignition. The case 12 and the sabot 30 can be provided respectively with a crimp 24 and a stepped portion 48 in order to limit travel of the sabot 30 out of the case.

Claims

1. A cartridge 10 for insertion into a firearm having a barrel with an inner bore and a firearm chamber 102, the firearm chamber 102 having an annular step 100 at its forward end, the inner diameter of such step bounding the inner bore of the barrel of the firearm, comprising

(1) a cartridge case having a base end 16 and front end 26 and an inner diameter at said front end 26;

(2) a source 14 for propellant gas within the cartridge 10;

(3) a piston 30 having a substantially closed rearward end, wherein said rearward end is sealingly positioned within said cartridge case 12 at a location spaced from the base end 16 of the cartridge case 12 and defining a closed cavity 22 within the cartridge case 12, said cavity 22 containing the source for propellant gas, the piston 30 having a front piston end 40 bounded by an outer, annular shoulder 76 defining the forwardmost portion of the piston 30, said front piston end 40 extending forward of the front end 26 of the case 12, said annular shoulder 76 having a diameter that is larger than the inner diameter of the case 12 at its front end 26 and larger than the inner diameter of the step 100 at the forward end of the firearm chamber 102; and

(4) gas passage means, extending from said closed cavity 22 through said piston 30, to permit gas generated within the cavity 22 subsequent to firing of the cartridge 10 to pass outwardly from the front piston end 40 of the piston,

at least a portion of said cartridge case 12 being slidable on said piston 30, and means for limiting sliding displacement in the rearward direction of the case 12 with respect to said piston 30 upon firing of the cartridge 10.

2. A cartridge 10 as in claim 1 wherein the means for limiting sliding displacement is provided by:

(1) the piston 30 being provided with a sidewall 81 with an inwardly formed step 48 within the rear portion 32 of the piston 30, such step extending to a point that is short of the rearward end 72 of the piston 30; and

(2) the case 12 having a wall 32 which is provided with an inwardly displaced flange 24 to engage with the inwardly formed step 48,

whereby the case 12 is slidingly displaceable on the piston 30 along the length of the inwardly formed step 48 without disengaging therefrom.

3. A cartridge as in claim 1 or 2 wherein before firing said piston 30 and case 12 are in contact with each other whereby said gas passage means is initially occluded, said gas passage means becoming opened upon displacement of the cartridge case 12 rearwardly with respect to the piston 30.

4. A cartridge as in claim 1 wherein:

(a) the piston 30 is provided within its sidewall 81 with an inwardly formed step 48 having a forward end 48a within the rear portion 32 of the piston 30;

(b) the sidewall 81 of the piston 30 is provided with at least one groove 64 in its rear portion 32 that extends from the rearward end 72 of the piston 30 to a terminal end 84 for the at least one groove 64 at a position intermediate the rearward end 72 of the piston 30 and the forward end 48a of the inwardly formed step said at least one groove 64 being connected to said step 48;

(c) partial gas passage means 44a extends from the forward end of the piston 30 to the step 48 to provide a passageway to the inwardly formed step 48,

whereby upon rearward displacement of the cartridge case 12 with respect to the piston 30, propellant gas flows from the closed cavity 12 out through the forward end 80 of the piston 30 through the at least one groove 64, the step 48 and the partial gas passage means 44a.

5. A cartridge as in claims 1 or 2 wherein:

(1) the piston 30 is provided within its sidewall 81 with an inwardly formed stepped surface 71 within the rearward portion 32 of the piston 30, such stepped surface 71 extending to the rearward end 72 of the piston;

(2) the wall 34 of the case 12 is provided with a thicker sidewall 34a overlying and sealingly engaging with a sliding fit with the stepped surface 71;

(3) the wall 34 of the case 12 is provided with thinner portion 62 to engage with the sidewall of the piston 30 forward of the stepped surface 71; and

(4) indirect gas passage means 44a extends from the forward end of the piston 30 to provide a passageway to the inwardly formed stepped surface 71 short of the rearward end 72 of the piston 30,

whereby upon firing and rearward displacement of the cartridge case 12 with respect to the piston 30, propellant gas flows from the closed cavity 12 out through the forward end 80 of the piston 30.

6. A cartridge as in claims 1 or 2, wherein said gas passage means comprises both indirect gas passage means 44a which are initially occluded and a supplementary direct gas passage 44 extending through the piston 30 from the cavity 12 to the forward end of the piston 30 whereby propellant gas will pass directly through said direct gas passage 44 during the period that indirect gas passage means 44a are occluded.

7. A cartridge as in claim 6 wherein the direct passage 44 is dimensioned to allow the propellant gas to carry a projectile 60 beyond the muzzle of the barrel in the time taken for the indirect gas passage means 44a to become opened.

8. A cartridge as in claim 6 wherein the direct passage 44 is dimensioned to allow the propellant gas to carry a projectile 60 part way along the barrel towards the muzzle of the barrel in the time taken for the indirect gas passage means 44a to become opened.

9. A cartridge as in claims 1, 2 or 4 having a primer wherein said primer constitutes the supply of propellant gas.

10. A cartridge as in claim 9, including an additional propellant gas material in said cavity.

11. A cartridge as in claims 1, 2 or 4 including a projectile in the forward end of said piston.

12. A cartridge as in claim 2 wherein the inwardly formed step 48 has a forward end 48a and comprising:

(a) at least one groove 64 formed in the sidewall 81 of the piston 30 in its rear portion 32, said at least one groove 64 extending from the rearward end 72 of the piston 30 to a terminal end 84 for the at least one groove 64 at a position intermediate the rearward end 72 of the piston 30 and the end 48a of the inwardly formed step 48, said at least one groove being connected to said step 48; and

(b) partial gas passage means 44a extending from the forward end of the piston 30 to the step 48 to provide a passageway to the inwardly formed step 48,

whereby upon rearward displacement of the cartridge case 12 with respect to the piston 30, propellant gas flows from the closed cavity 12 out through the forward end 80 of the piston 30.

13. A cartridge 10 as in claims 1, 2 or 4 wherein said case 12 has an outer diameter at its front end 40 and the diameter of the annular shoulder 76 is substantially equal to said outer diameter of the case 12 at its front end.