When they installed a bomber cannon on an M1 Garand, the Japanese nicknamed them “monster weapons”.

The machine gun crews would be crucial, but the M1919 A6 was too slow, too heavy, and too vulnerable. Three weeks earlier, Grevich had consulted with his company commander. He had explained that the M1919 A6 required three men to operate effectively: a gunner, a gunner’s assistant for ammunition supply, and an ammunition carrier to transport spare belts. If the gunner was incapacitated, the entire gun crew was paralyzed.

The weapon was also difficult to reposition during an assault. The Marines had to stop, set up the bipod, and then begin firing. By that time, the Japanese defenders had already spotted their position. The company commander listened. Then he asked Grevich if he had a solution. Grevich did. He had seen it in action at Bugganville thirteen months earlier.

In November 1943, he was serving with the 3rd Parachute Battalion. The Marines had recovered M2 aircraft machine guns from crashed dive bombers. These weapons were designed to be mounted on SBD Dauntless aircraft. They fired .30 caliber rounds at a rate of 200 rounds per minute, three times faster than the M1919 A6. Their barrels were lighter. These weapons were designed to be cooled by an airflow of 480 km/h (300 mph) in combat.

In Bugganville, a Marine named Private Bill Colby had simply attached a bipod to an AM2 and was using it as a ground weapon. It worked, but the weapon retained its ergonomic “shovel” grips. Without a stock or a proper trigger, it was functional, but unwieldy. Gravich and his section leader, Lieutenant Philip Gray, on the other hand, had modified an A&M M2 more extensively.

They added an M1 Garand rifle stock, a bipod, and a custom-made trigger. The weapon functioned, but the 3rd Parachute Battalion was disbanded before it could see combat. Grevich was reassigned to the 28th Marine Regiment. The modified A&M2 was left behind. In November 1944, Grevich stood in that warehouse, reminiscing about the weapon’s capabilities.

The 28th Marine Regiment was due to land at Ewima in less than three months. The M1919 A6 wouldn’t suffice. They needed the AM2 modification, but this time, they required six: one for each infantry section of G Company, one for the demolition section, and one for themselves. Their company commander approved the plan, as did the battalion commander.