Brit, how do you manage to get a hold of the import license for a tank? Would it be considered a 'prohibited firearm? Don't you have to do something to permanently alter the breach so it cannot fire any known caliber of shell? Wouldn't it then be plausible enough to develop a tank sized M203 round, making sure it's not the size of any common caliber, adding an inner barrel, etc?
I want I want I want!