Mossberg 190 Conversion

Would anybody have any thoughts on the safety of converting a Mossberg 190 bolt action 12 or 20 ga. to a scoped slug gun? Will the action handle (mostly) slug only use? A co-worker inhereted a couple and is selling them cheap. Another co-worker suggested this and my thoughts went into the safety issues. He was thinking of cutting the barrel back a bit and mounting the scope to make an inexpensive slug gun. I've seen them before but have never fired one.

Thanks!