Bunny's shotgun got him killed. He might have fared better against the Vietcong with a machine gun.
You've seen Guy Standeven in something because the man was in everything.

I guess it was for close range fights like grenade launchers are for long range fights. I doubt the shotgun is much use beyond about 75 yards, and it might be foolish to use a grenade launcher within 75 yards. My numbers are likely off.

It was perhaps emblematic of Bunny - an individualist wild card. I don't think the platoon was particularly well run, anyway, with that lieutenant being useless, plus the Barnes-Elias conflict, so Bunny might have been able to get away with an eccentric weapon choice.
"Chicken soup - with a beep straw."

i read navy seals in Vietnam preferred the shotgun going on point pointman, but I rarely saw bunny on point. also I think he was also a private so I doubt he'd be allowed to choose what weapon he wants - tho ive never been the army so I don't know beep

Shotguns were sometimes issued although they were favoured by Special Forces, often for tasks like ambushing VC couriers in the jungle or by Navy SEALs on boats patrolling the Mekong, to repel boarding attempts. It is really only a weapon for close range fighting and he would have been better using a rifle.
"Chicken soup - with a beep straw."