The endurance test is intended to determine the number of firings (of ammunition complying with SAAMI pressure specifications for service loads) required to induce a catastrophic failure of the gun assembly. In order to insure the ammunition used in these tests includes representations of moderately high pressure firings periodically encountered in service loads, a high pressure test (proof) cartridge will be fired after each 100 firings. Firings are to proceed in 500 round increments (including 5 proof cartridges) until catastrophic failure is induced or until a total of 10,000 firings without catastrophic failure have been performed. After each 500 round increment the gun is to be thoroughly cleaned and inspected. Repairs and component replacement during this test are limited to non-pressure containing features of the gun (extractor, firing pin, ejector, etc.). Specifically exempted from such repairs and replacement are the receiver (frame), barrel, bolt, components and features of the locking system, etc. Firings from multi-chambered guns will be conducted in cycles of one firing from each chamber to insure that equal numbers of firings have been conducted from each chamber throughout the test (including PROOF firings).