with the realization that there are probably many laws of physics and international law broken by this... http://www.docsmachine.com/nonPB/mortar.html
for when you want to shoot something with a real kick, dont reach for the .500
technically legal -- smooth bore black powder rifle... it DOES use pyrodex, but i dunno if A. i would trust it, and B. the cops would find you so intelligent
Nothing illegal about owning or building such a thing in the states, as it's muzzleloading. But using it would probably be treated the same way as using a firearm. Probablythe same as robbing a bank with a flintlock, as one guy in the '30s did on a dare.
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Trust is earned, not... GIVEN away. - Worf