RE: slug guns
Can only wonder if you've even fired a slug gun, let alone killed anything with one....obvious from what you've so willingly posted so far.
The common concensous so far, which I happen to be part of, isthat the Hornady SST's work well, and that would suggest trying themfirst in this particular make of slug gun. That's valuable to the one asking the questions, and only requires a box or two to find out....since he needs a place to start anyway, to being with.
You've left the man with no answers to any of his questions, beyond, that he is basically on his own.
I'm sure he appreciates it though........