TARGETING AND ACCURACY (PATTERN): At a range of 40 yards (+/- one foot) aim shall be taken at the center of a pattern sheet not less than 40 nor more than 60 inches square. The shot pattern shall be such that not less than 33 1/3 per cent of the shot pellets shall be within or cut the edge of a 30-inch diameter circle for accuracy (pattern), drawn entirely on the pattern sheet so as to enclose the most shot. Five patterns shall be fired from each gun and the average must be as specified. The guns shall be hand held during firing, or mounted in a fixture that simulates hand firing. Ammunition shall be as specified in 3.17.3. ENDURANCE TEST (LOT ACCEPTANCE) Shotguns shall be capable of withstanding the firing of 3,000 rounds with no unserviceable or broken parts and no more than three (3) malfunctions using standard commercial 12-gauge, 2 3/4 inch, 00 buckshot (9 pellets), maximum load shells. Type I shotguns shall include M7 bayonet and scabbard as specified in 3.3.1.a. ROUGH HANDLING After completion of the performance test, three weapons shall be chosen and subjected to the rough handling test. Each weapon will have the safety "on", a primed cartridge case in the chamber, and a fully loaded magazine. One weapon shall be conditioned at -20 degrees F, one at ambient, and one at +120 degrees F for a minimum of four hours prior to the test. The weapons shall be dropped a minimum of four feet (lowest point on the weapon to the drop surface) in each of the following five modes: Butt end down right side down left side down top side down 45 degree angle with verticle plane- butt end down The drop surface shall be 85 + 5 Durometer (Shore A) rubber mat, one inch thick, backed by concrete. At the test conclusion the weapon must be safe and serviceable and the primed shell shall not have fired. INTERCHANGEABILITY TEST: Shotguns shall be tested for interchangeability of repair parts (see 3.18) by disassembling the shotguns and placing parts of each kind in the same container. The ten shotguns shall then be reassembled using repair parts taken at random from each container and subjected to the functioning test of 4.6.3 and the headspace test of 4.6.2. HEAT SHIELD EFFECTIVENESS Type I shotguns shall be tested for heat shield effectiveness (see 3.3.3.e). The shotgun and its ammunition shall be conditioned at 78 degrees +/- 8 degrees F for a minimum of four hours. Then 25 rounds of standard, commercial, 12 gauge, 2 3/4 inch, 00 buckshot (9 pellets) maximun load shells shall be fired in not more than 3 minutes (rate of fire is to be approximately 1 shot every 5 seconds). Immediately after completion of the firing, the temperature of representative ares of the heat shield shall be measured. No measurement shall exceed initial temperature plus 40 degrees F. Areas to be measured and measuring equipment used shall be approved by the Government representative. At the discretion of the contractor, this test may be performed in conjunction with the endurance test (4.6.5). The 590 is a good shotgun, and Mossberg bills it as the only pumpgun to meet these specs. But wouldn't the Remington 870 seem to be able to pass this test also? There's a few more tests in the MILSPEC also, and a lot of manufacturing requirements.