GaugeMates
 

I saw this on the cabelas page on facebook and it is pretty cool. It makes it possible so you can shoot a smaller gauge then what your shotgun is made to shoot. Sure is interesting, have any of you tried it?

http://www.gaugemate.com/

I have a set of Browning Gauge Mates that are 12ga and accept a 20ga shell to be fired in it. The are only steel sleeves that drop in like a regular shell.
I shoot them in my Beretta and Kreighoff O/U trap guns for S&G's instead of using the drop in tubes. Really neat to see other peoples faces when I pop those yellow shells out of a 12ga gun!!