WOW ! i posted this same question on 3 other sites as well and it seems there are a number
of hunters that are very uninformed [MYSELF INCLUDED] about this question. SO,i did some googling and found alot more of the same confusion !
i also found the answer....seems like BRENNEKE designed the rifled slug to be able to shoot through any choke. the ribs on a rifled slug provide space for the slug to compress as it passes through.
heres the link to the site
http://www.brennekeusa.com/web/text/faq.html
by the way....i shot some slugs through it today and no splintered barrel !
good group at 50 yds but they did drop about a foot and spread out some at 100 yds.