David,
The Magna-Port does work very well. Good rig for the fly fishing stuff. I have a Diamond-D rig similar to yours and hardly notice that I am wearing the piece.

Thinking of a very hairy caliber/gun combination,a friend of mine has an American Derringer chambered in 0ne barrel for 410,the lower barrel in......................45-70.

I think that the trick is to have the bear fire it!!!!!!!!!

Wayne