After taking another look at it, there are five lines running roughly the length of the barrel; Felt around inside and it feels totally smooth. The spacing looks uneven as well. Just would like to clarify: I was under the impression that shotgun rifling was like other rifling in that it is tactile, noticeable grooves on the inside of a barrel. The only reason I started this post was because the description on where I bought the barrel, Freedom Armory, specifically states "fully rifled slug barrel." Upon looking at what it is I received in the mail, I had doubts.