Weapon conversion question.

[stg58fal]

Steal the stats from the USAS-12 and adjust mag capacity, ROF, etc, or shamelessly rip off the H&K CAWS.

Then spend the rest of the campaign showing him just how friggin useless a shotgun is in combat outside of a very few instances.

Shotgun < rifle

There are a few good uses for them in urban warfare. I still prefer a rifle or SAW, but shotguns have some utility.