RE: RIFLED SLUGS IN A RIFLED BARREL
It will not harm it, but it isn't very fun to clean. My slug gun will shoot rifled slugs pretty accurately if I choose the right ones, but only for about 4 shots then the barrel fouls out. It will fill the grooves with lead and start to effect accuracy. Then you have to clean the barrel, which will be a chore compared to shooting sabots.
Not to mention the newer sabot ammo has better ballistics and better designed bullets.
Paul