RE: Rifled -v- Sabot Slugs
It will not hurt the barrel, but it will foul out pretty fast, like accuracy will drop off after 4 or 5 shots in most cases. And they are not fun to clean, makes a real mess. As long as you clean the gun real well though it will not actually damage the barrel.
Mine shoots pretty well with 3 inch winchester rifled slugs. I can over lap holes at 100 yards off from a bench for three shots. After that things fall off because the barrel is dirty.
Keep in mind you will not get the same performance from a simple rifled slug as you would out of modern sabot shooting a controlled expansion bullet. They are obviously still capable of killing deer though. Mine tends to like Winchester Platinums.
Rifled slugs cost about 3 bucks a box, and modern sabot loads cost closer to 15 bucks for 5 shells!
Paul