OK, it took me a while to sort through the Firequest catalog.
You were talking about this gadget, a "shellholder" 12 gauge firing device for use as a perimeter alarm.
I bought one of these a few years ago from Shomer-tec, just to satisfy my curiousity.
I still haven't sorted out Firequest's price. I see this:
HV-5 Pest Control System
Item # HV005 $44.99 $34.99 On Sale!
3 Units Per Package $11.99 $9.99 On Sale!
Does it mean three of these gadgets are $9.99 or that they're $9.99 apiece? If so, what's the line above, with sale price of $34.99? If the items are under ten bucks, they're definitely cheaper than Shomer-tec.
A friend and I were curious. He's a Machinist, so he experimented with making two or three more.
As I understand it, this is a SHELLHOLDER only. That should be legal. We've only tried them with the "game control" shells that pop a charge up in the air, then it goes bang --- and with some 6 dram equivalent black powder blanks. Most recently, I noticed the black powder blank (which is in a plastic shell, roll crimped with a front card wad) made a flash and bang, and never even blew out the front wad. It just split the case in 3 or 4 places.
If someone's curious, I'll be happy to set one off with a live 12 gauge round in it. I'll keep the tree between me and the device, maybe set up some cardboard, light wallboard, etc. around it to see what happens.
I rather expect, since the shot charge outweights the device and there's no containment, the shell will split open and the device itself will receive some downforce. I don't expect shot to be launched effectively.
Where you'd get into trouble, would be if you slipped a piece of 3/4" pipe over the shell, making a crude chamber and barrel. Now you have device that can be roughly aimed and will qualify as an illegal short barreled shotgun. Aside from the fact that booby traps are illegal, nondescriminating, and you can harm an innocent and/or lose the farm ---- does anyone here want to end up like Randy, Sammy or Vicki Weaver? The noisemaker is fine, but I'd have to recommend against turning it into a harmful booby trap.
Knowing how to do this, make VietCong "footbreakers," rig fences & locks to electrocute people, set punji stakes, etc. may be useful skills when TEOTWAWKI comes along. But as long as civilization is hanging together, this stuff will just buy you trouble.