Back during the Moro Insurrection, our soldiers had trouble dropping those fanatical Islamic Extremists with 30-40 Krags, 38 New Armies, etc, before the Moros carved them up. The 45 ACP Government model was developed because of this.
A pay train, IIRC, was ambushed by a group of Juramentados, fundamentalists sworn to kill until they died. The 6 solders in the escort had Model 97 Winchesters and 00 buck. No soldiers were hurt, the final score was 11-0.
Shotguns, whether issued or not, keep turning up in hot zones. Stopping power is unequalled, MOA is simple, and the soldiers have faith in the shotgun's ability to protect them and accomplish the mission.