RE: rifled slug barrel ammo
9 bucks a box for sabots, you should consider yourself lucky. That is the lower end around here.
I shoot rifled slugs out of my H&R, they work pretty well for the money. Mine only goes about 3 shots or so before the accuracy falls off and the gun needs to be cleaned though. It will not hurt it at all, but but it is a mess when you clean it.
Most rifled slugs don't offer any where near the ballistics or bullet performance of a good saboted slug though. Some of the more modern ones can be between 10-14 bucks a box. But the performance is worth it to some. They are more expensive then they should be in my opinion. I don't see how they justify it.
Paul