Was it an assault shotgun or a sporting shotgun?
I carried a shotgun for awhile as an infantryman in Viet Nam.
I don’t remember now why. It was okay for close in Jungle but not very effective crossing rice paddies or open fields and it was difficult to keep clean and keep from rusting. But that was just my experience I am sure others had different experiences.
Went back to the M16.
Al Capp tried to persuade his high-placed contacts in gov't to make shotguns the standard issue weapon in Vietnam.
Your experience shows they were right not to.