We used to have a 60 foot tall cinder block silo here, that was back in the day when my uncle had a reproduction cannon from Dixie Gun Works, it shot 2 5/16 diameter orange juice concentrate cans full of concrete with a charge of four ounces of 4F black powder.
When it came time to knock the silo down I borrowed the cannon and made up a bunch of projectiles and bought about five pounds of powder, it turned into a real party about ten guys showed up and so did a LOT of beer.
Turned out them juice cans would go through both sides of them cinder blocks, lots of the neighbors either came over or drove past, a cop even showed up, he was pretty much at a loss, he had to get on the radio to the sheriff and explain what we were doing to find out if it was all legal.
The sheriff told him as long as they got a sufficient back stop and aint to drunk to use the thing responsibly it aint against the law to shoot a silo down with a cannon, it took about 25 rounds and four or five hours what with the festivities and all, the cop even stayed for a few rounds, finally that old silo had had enough and it was just about like one of those implosions it pretty much fell right on itself.
My uncle was an engineer for Howmet Turbine, Howmet bought a big X-Ray machine and he ran the cannon tube through it, turns out that tube had so many hollows and inclusions it was a miracle it never blew up on anybody, they filled the bore with concrete and turned it into a lawn ornament.
