r/guns – Was gifted a 12 ga H&R “Slug Master”. Question about the ammunition

My brother just gifted me a 12 ga H&R slug master. I’ve shot many different rifles and shotguns before, but this is actually the first shotgun I’ve personally owned. So, I’ve never really had to worry about the ammunition for the firearms I was shooting before. My main concern is whether this is purely meant to fire slugs, or if it can shoot shells as well. My brother emphasized that this gun has rifle boring and is very accurate with slugs, but never explicitly told me if it can only shoot slugs. The name and ofc the boring leads me to believe it can only shoot slugs, but I just wanted to ask if shells will mess it up at all or if shells simply aren’t taking advantage of the accuracy capabilities

Side note, any idea what this is worth? No intention of selling it, my brother said he got it second hand for $150 and just curious about whether or not he got a ridiculously good deal