Looking at curl's muzzle I think the twist rate is steeper than the Carlson 6" rifled extension--and I get lead smear big time unless I shoot slower slug loads than the 1350-1600 fps factory offerings I see out there. The slug is just moving too fast by the time it engages the rifling. I even see it on my 20" barrel with 6 inch rifled extension. I don't know how the paradox could fare much differently given those factory speeds. Fully rifled barrels avoid the problem in the first place. (strangely, the best slug performance I get is with an ancient BBF over under combo with no rifling at all in the shotgun barrel--but it shoots a 2" group at 100 yds with the old Activ slugs, and the same group two inches farther to the left with the classic Brennekes. Good luck!
