RU225040U1 - Rifle test cartridge of rimfire caliber 5.6 mm - Google Patents

Abstract

The utility model relates to test rifle cartridges of rimfire, 5.6 mm caliber, used to test the strength of locking units of sporting and hunting rifles in accordance with the requirements of GOST 50530-15 by shooting two test cartridges from the above-mentioned type of rifles during acceptance tests.

The test rimfire rifle cartridge of 5.6 mm caliber contains a lead non-jacketed bullet, a case with a reinforced bottom, a powder charge and an igniter primer. At a distance of (0.45-0.51)d from the bottom plane, the sleeve has a thickening due to the fact that its inner surface is located at an angle of 4°3' to the outer one. At a distance of 1.5 mm from the bottom plane, the sleeve has a thickness of (0.065...0.069)d. The thickness of the bottom of the case is (0.07-0.075)d, with the hardness of the bottom of the case being (90...120)HV, where d is the caliber of the cartridge. The strength characteristics of the liner are ensured in accordance with modern requirements, while reducing the material consumption of the liner and eliminating defects in the stamping operation of the liner flange. 1 ill.

Description

The utility model relates to test rifle cartridges of rimfire, 5.6 mm caliber, used to test the strength of locking units of sporting and hunting rifles in accordance with the requirements of GOST 50530-15 by shooting two test cartridges from the above-mentioned type of rifles during acceptance tests.

Test rifle cartridges of 5.6 mm caliber are known (application 2004130821/02 dated 10.22.2004, MPK F42B 5/34), containing a sleeve whose body wall profile has two sections, the straight lines of which are located at angles to the longitudinal axis of the sleeve 0 °26' and 5° and are interconnected by radii (0.1-0.3)d and (0.05-0.06)d, and the ratio of the length of the lower section of the body to the total length of the sleeve is 0.10-0, 15, while the thickness of the body wall at the flange is equal to (0.07-0.08)d with a hardness of the lower section (110-135)HV1, and the thickness of the bottom is equal to (0.075-0.085)d with a hardness of (150-175)HV, where d is the caliber of the cartridge.

These cartridges were produced in the 80s of the 20th century and supplied to arms factories of the USSR. The design and technical characteristics (linear dimensions of the cartridge and pressure in the bore when fired) complied with the requirements of the Permanent International Commission (PIC) of the Brussels Convention on the Mutual Recognition of Test Marks for Handguns. However, the production of cartridges was subsequently discontinued.

The disadvantages of this cartridge are:

- the use of brass tape with a thickness of 0.5 mm (DPRKhM 0.5×91 L-68 GOST 1018-77) for the manufacture of cartridge cases, which is 10% greater than the thickness of the tape (0.45 mm) used for the manufacture of cartridge cases of the inventive cartridge;

- the presence of technological difficulties in the operation of forming (stamping) the sleeve flange with ensuring the dimensions specified in the drawing, due to an increase in the wall thickness of the semi-finished hood, which led to an increase in the percentage of defects in this operation in terms of height, flange diameter and internal geometry of the sleeve flange, as well as loss of time for setting up equipment;

- the inconvenience of using brass strips of different thicknesses at an enterprise for the manufacture of cartridge cases with the same external but different internal dimensions for different cartridge designs inevitably increases the risk of clogging batches of cartridges of one design with cartridges of another design;

- according to modern requirements of the PMK of the Brussels Convention, more stringent requirements are imposed on the pressure developed when firing test cartridges. For example, the maximum maximum pressure increased from 2158 bar to 2550 bar. Changing the design of the test cartridge sleeve by further increasing the thickness of the sleeve wall in the bottom part will entail an increase in technological difficulties in the flange stamping operation.

The technical result of the proposed utility model is to create a design for a reinforced cartridge case for a rifle test rimfire cartridge, mainly of 5.6 mm caliber, which allows reducing the material consumption of the case and losses from defects in the stamping operation of the case flange, while ensuring strength characteristics in accordance with modern requirements of the Brussels PMK Convention (Pmax ≤ 2550 bar).

This result is ensured by the fact that at a distance of (0.45-0.51)d from the bottom the walls of the liner are thickened due to the fact that their inner surface is located at an angle of 4°3' to the outer one, at a distance of 1.5 mm from the plane of the bottom, the walls of the sleeve have a thickness of (0.065...0.069)d, and the thickness of the bottom of the sleeve is (0.07-0.075)d, with the hardness of the bottom of the sleeve - (90...120)HV, where d is the caliber of the cartridge.

These essential features are interrelated. Changing any of them affects the implementation of the task of the proposed utility model.

Increasing the length of the reinforced bottom section of the liner by more than 0.5d is impractical, because will not increase the strength of the sleeve, but will increase the material consumption of the structure.

Reducing the length of the reinforced bottom section of the liner to less than 0.45d is impractical, because will make it difficult to measure wall thickness at a distance of 1.5 mm from the bottom plane during production control.

Increasing the thickness of the liner wall at a distance of 1.5 mm from the bottom plane by more than 0.069d will increase the strength of the liner, but will increase the material consumption of the structure.

Reducing the thickness of the case wall at a distance of 1.5 mm from the bottom plane to less than 0.065d will negatively affect the strength of the case when fired, i.e. will lead to ruptures, which is an unacceptable defect of the cartridge.

Increasing the thickness of the bottom of the sleeve by more than 0.075d is impractical, because will increase the material consumption of the structure.

Reducing the thickness of the bottom of the sleeve to less than 0.07d is impractical, because will negatively affect the strength of the cartridge case when fired, taking into account the developed maximum pressure of powder gases of 2550 bar, which is 1.96 times more than that of commercial 5.6 mm cartridges with a similar bottom thickness.

An increase in the hardness of the bottom of the case by more than 120 HV increases the magnitude of residual stresses in the walls of the case, and, consequently, increases the likelihood of corrosion cracking of brass during storage of cartridges, and, ultimately, a decrease in the strength of the cases. Reducing the hardness of the bottom of the cartridge case to less than 90 HV increases the likelihood of the bottom being pierced by the firing pin of the weapon, which is an unacceptable defect of the cartridge.

The drawing shows a longitudinal section of a test cartridge located in the barrel of a rifle with a closed bolt.

The cartridge consists of a cartridge case 1, which has a reinforced bottom part with an igniter primer 2, fixed in the bottom part of the case, a propellant charge 3 and a shellless bullet 4.

The cartridge functions as follows. When the bolt striker impacts the edge of the case flange, the igniter primer 2 is triggered, igniting the propellant charge 3. The gases formed during the combustion of the propellant charge 3 push the bullet 4 out of the barrel. At the same time, the bolt of the weapon and the chamber are exposed to increased pressure from the test cartridge, almost 2 times greater than that of sports or hunting cartridges of this caliber. After two test shots from commercial rifles, the technical condition of the rifle bolt is determined. If it meets the requirements of the technical documentation for the weapon, the rifle is considered to have passed the test.

Claims (1)

A test rifle cartridge of rimfire of 5.6 mm caliber, containing a lead shellless bullet, a cartridge case with a reinforced bottom part, a powder charge and an igniter primer, characterized in that at a distance of (0.45-0.51)d from the plane of the bottom the cartridge case has thickening due to the fact that its inner surface is located at an angle of 4°3' to the outer one, while at a distance of 1.5 mm from the bottom plane the sleeve has a thickness of (0.065...0.069)d, and the thickness of the bottom part of the sleeve is (0.07 -0.075)d, with case bottom hardness - (90…120)HV, where d is the caliber of the cartridge.

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