The gunners had learned to control the overheating problem: bursts of 5 to 10 rounds, followed by 15 seconds of cooling. The technique proved effective. The guns remained at their optimal operating temperature. The weapons maintained their proper function. The tactical advantage was considerable. Standard American machine guns required a three-man crew.
One gunner, one assistant for feeding ammunition, and one carrier for spare ammunition belts. The modified weapons required only one marine. The gunner carried both the weapon and the ammunition. The 100-round magazine eliminated the need for an assistant for feeding. Thus, rifle sections could maintain their full complement of men while still benefiting from machine gun support. The weight reduction was also significant: 11.3 kg instead of 14.5 kg.
A marine could carry the weapon while moving quickly over rough terrain. The first section gunner engaged a pillbox complex northeast of Green Beach at 11:30 a.m. The position had three overlapping firing ports. The Japanese defenders had a clear line of fire covering the access to the terraces. The gunner advanced to within 60 meters, fired a 15-round burst at the central port, moved left, fired at the second port, moved right, and fired at the third port.
Total engagement time: 12 seconds. All three ports remained silent. The section advanced through the breach. The section’s second gunner joined a demolition team at 12:00. The team’s mission was to destroy a concrete bunker built at the base of a terrace. The bunker had a steel door and reinforced walls.
The demolition team was supposed to place charges directly against the door, but Japanese fire from adjacent positions prevented any approach. The gunner neutralized four positions in succession. Short bursts, rapid target changes. The team reached the bunker, placed the charges, and withdrew. The bunker was destroyed at 12:15 PM.
The machine gunner in the third section reached the overheating limit at 12:30 PM. He had been firing almost continuously for 90 minutes. The barrel temperature exceeded safety thresholds. The weapon jammed. The machine gunner cleared the jam and attempted to resume firing. The weapon jammed again. He then ceased firing and allowed the barrel to cool for 10 minutes.
The weapon resumed operation. But this incident highlighted its main limitation: the ANM2’s gun was designed for short bursts in aerial combat, not for sustained ground fire. The gunners had to be disciplined: short bursts, long pauses. It was the only way to keep the weapon operational.
The demolition section’s machine gunner used his weapon to provide cover for the engineering teams clearing obstacles. The Japanese defenders had laid mines and barbed wire on the access routes. The sappers had to clear these obstacles under enemy fire. The machine gunner provided suppression fire. He fired on the Japanese positions, forcing the defenders to take cover.
The engineers completed their work. By 1:00 p.m., three major obstacle zones were cleared. The 28th Marine Regiment advanced further inland. Grevich continued to engage targets throughout the afternoon. Bettyanne had fired approximately 400 rounds by 2:00 p.m. The barrel showed signs of wear, heat discoloration near the chamber, and slight longitudinal deformation, but the weapon was still functional.
Gravich closely monitored the gun. He reduced the duration of its bursts to five rounds and increased the cool-down time to 20 seconds. This new firing pattern kept the gun within tolerance limits. By mid-afternoon, Tony Stein’s performance on the right flank had become remarkable. Stein was using his modified weapon to directly attack the pillboxes.
His technique was aggressive. He would locate a bunker, approach at close range, fire sustained bursts at the gun port, then storm the position with grenades while the Japanese defenders were neutralized. The method was effective, but it quickly depleted ammunition. Stein made eight trips back and forth to the beach to resupply before 3 p.m.
Each trip covered approximately 200 meters under enemy fire. Each time, he brought back wounded Marines, unable to walk. The psychological impact of these weapons became evident during the afternoon fighting. The Japanese defenders reacted differently to these modified weapons than to standard machine guns.
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