The 45/410 barrel is rifled, but as Spanky said, the long jump to the rifling would stifle the +P loads enough they shouldn't be a problem, they're no higher pressure than 44mags which come on SB1 frame, so neither the frame or the barrel should have a problem with them. If you have the barrel drilled and tapped for a scope rail, you shouldn't have any problems with 50yd deer, maybe ever 75-100yds, give it a try, some have said with optics they can hit clay birds at 100yds, with the right load it could be good deer medicine.
Tim