Non PA combat shotgun/pepper shaker build (ghoul)

I like using combat shotgun with explosive for events to tag as many enemies as possible for exp and would like to use pepper shaker to melt bosses....I'm having trouble finding builds for it. or maybe im just going at it all wrong??? I wanna be able to tag as many enemies as possible but also do as much damage as i can to bosses...any help would be appreciated. would like to stick to shotguns just because it's different but i would be open to switch to different weapons...like i said just wanna tag as many enemies as possible while doing decent damage but also be able to melt bosses