jaughtman...i think you are talking about the really short adapters that look like a 12 gauge shell that you stuff a 20 gauge into and shoot through a 12....mine are called Little Skeeters. The 12 to 20 were fine and 12 to 28 were just OK, ...never tried the 12 to 410
I have some that I used early on to shoot the 20 events in Skeet. The targets that did not break were my fault. That is about the most positive thing I can say about them. Other than that, they are a PITA and nasty to use, you get burnt powder all over your hands. You need to carry some kind of poker to push out the old shells. They get old pretty fast. If you just want to fool around they are kinda OK.
IMO, none of the short tubes really work well. If you have a high quality O/U, a fitted tube set at around 1800-2000 bucks is a great investment. They are really like having a 20, 28, and a 410 that look exactly like your O/U.