I have a mossberg 500 with rifled slug barrel. No matter what I tryed in that gun I always went back to the good old Federal sabot slug. They always produced good groups. I tryed the Brenekes for 3-4 yrs and found there was always an occasional flyer and groups from the 500 barrel and my Rem 870 slug gun were never that great. I've heard the same from other guys. Best thing to do is buy about 3-4 slug brands and go and shoot em up to find what that barrel likes. Sabots are the way to go in a rifled barrel!

Good Luck - Let us know what happens. There are always guys on the MB looking for info on this subject.