BBF, two years ago when finances were non existant I used a bunch of winchester rifled slugs I had and resighted my Rem 870 rifled slug barrel. I must have had over 50 of those old slugs (given to me from a friend) and I ran 30 through it. I verified I was on the paper at 25 yards and then moved the target out to 50 yards. When I started shooting I got nice tight groups, I don't remember the measurement, but no bigger than an apple from a bench. After about 10 rounds things started to open up a little. By 20 rounds it had opened up alot. The outer target circle was 12" diameter and it was now putting them all over it. If memory serves slug 30, and I think slug 29 and 30, didn't even hit the paper.
When I got home I pulled off the barrel and started cleaning it. I had to use alot of solvent and elbow grease to get the lead out of the rifling, ALOT. I think it took a couple hours even. If I had it to do again I would have used a penetrating oil like pb blaster or something like that (maybe even wd45) that would penetrate between the lead and the rifling. I knew a guy that used penetrating oil and it loosened the lead right up and after setting wet over nigth the lead pushed right out. Very little elbow grease!!!
After I had the barrel clean I fired a few slugs threw it, grouped just fine. I cleaned the barrel out again, this time with only three slugs through it the barrel wasn't bad at all to clean. Given the accuracy I held my shots to 75 max yards. I'd only shot to 50, so I really didn't feel confident to 75, but given it's 50 yards accuracy I thought the slug should hold together to 75 yards. Around that distance I calculated it would be transitioning from super sonic to sub sonic velocities and if it didn't have the necessary rotation the slug would destabilize and began to tumble and gone who knows where.
That year I counted over 10 shot opportunities at deer 100 to 150 yards... I never fired a shot. Two weeks after season ended I ordered an Ultra slug 20, sold some other stuff to pay for it, and haven't looked back. But if something happened to my ultra slug 20 and I didn't have any 12 gauge sabots for my rifled 870 I'd grab a box of rifled slugs, a bottle of bore cleaner, pb blaster, and a target and get myself ready to fill the freezer.
Hope this helps!
later,
scruffy