Оффтопик:http://en.wikipedia.org/wiki/M4_cannonHowever, the overall length of the armor-piercing projectiles, M51 and M74, which were used in the M3A1, M5A1 and M6 tank and antitank guns, was too great to permit their use in the M4 gun and the 37 mm (1.46 in) armor-piercing shot, M80, was developed and standardized.