Hi Guys,
The "Masterkey" is indeed a cutdown Rem. 870. There are a couple of variants, a barrel mount like the M203, and the RIS version. The barrel mount weighs in just a bit heavier than an M203 at about 5 1/2 pounds, mount included. Not sure what the exact RIS version weighs, probably about the same. The one I used had the barrel mount.
They actually are handy depending on the situation. Especially for breaching with a "TKO" round. Only bad thing is since the mag tube has been cut down it only handles 3 rounds. And you won't be making any rapid-fire movements with one. It handles about like an M203 only with little meaner recoil.
Cool, yup. Unwieldy, yep, until you get used to it. Practical, depending on the situation definately. Personally, I like them (and got skulled for it here [;)]) for what they're designed for. Are they worth $1,500+ just to own one? Not in my opinion.
-SARguy