Hi, Jerry, I have Chambermates 12-20 ga. The shot pattern is similar to the pattern with 12 ga shells in my Lanber u/o.
The Chambermates are more expensive than the other adapters but these have ejectors which hook onto the gun's and, an O ring to hold the Chambermate in place. The O rings come in different diameter to make a tight fit in different chambers. With the instructions come a chart of the O ring sizes so you can trot off to the Coop Ag Store to replace them when needed.
I do not reload the 20 ga Wally World hulls buy they are reloadable by the looks of them.
Mike
