M3/M3A1 Grease Gun In 1941, the US military began looking for an alternative for the Thompson submachine guns. In December of 1942, they adopted a new submachine gun, the M3. Built from an all-steel construction using mainly stamped parts, it fired from an open bolt and had simple controls. At first, soldiers were not so confident about their new weapon, they believed it looked crude and could not hold the powerful .45 ACP round. The M3 had a cocking handle on the side of the receiver, and its dust cover would work as a safety. They gave the weapon many nicknames, but the one that stuck was the “Grease Gun”, because it looked so similar to the tool. The M3 “Grease Gun” soon proved to be a reliable weapon, it was compact, light, had a controllable rate of fire of 450 rounds per minute, and it was cheap. It was favored by tankers, drivers, and even paratroopers due to its compact size. Even though the M3 was performing well, there was still some issues that needed to be fixed, so in December, 1944, the M3A1 was adopted. It was further simplified by removing the cocking handle and elongating the ejection port. The weapon was loaded by putting your finger in a groove on the bolt and pulling it back. Other things were added such as a guard for the magazine release, easier disassembly pieces, and a magazine loading tool on the stock. Overall, the M3 and M3A1 “Grease Gun” was well-liked by service personnel. The M3 served extensively through World War II and the Korean War. It was issued to the US and ARVN (Army of the Republic of Vietnam) forces in Vietnam prior to the adoption of the M16, and served tank crews from then on, into the Gulf War. Subscribe for more World War II videos! Get your copy of Simple History: World War II today! Thank you for all your support on the Simple History YouTube channel! If you enjoy the channel, please consider supporting us at Patreon.