It would be best not to use a full choke on a slug. Typically (best case), it could foul a sabot-type slug from doing its job and a rifled slug could be severely shaved on its way out the barrel. At worst, the slug could lodge and cause a real problem. <img src=icon_smile_sad.gif border=0 align=middle>

Some people sware by using the full choke, but I wouldn't want to chance it. My Mossberg recommends using an Improved Cylinder choke for slug use - and doing so has worked real well.