I have cousins that shoot deer at 100 yds. with smooth bores and no rifeled slugs! Just take your gun and buy 4-5 different brands of slugs, then shoot them to see which one patterns the best! If non of them pattern then you should go buy a rifeled barrel. I had a shotgun that would shoot any slug for crap so I ended up buying a gun with a rifeled barrel 20 gauge Ithica and it's right on at 100 yds. Try your gun first with different slugs!