If you can afford it, sure, why not?
Are you really okay with someone owning one of these? Ammo included?
You can actually have all that stuff... theres just a shit ton of hoops to jump through... I knew a guy that had a 203 with HE rounds. He paid a $200 tax for each one of them and a $200 tax to buy the 203. And there's plenty of guys out there with live artillery.
When I mentioned artillery I was certainly not thinking of a grenade launcher. I am thinking more of the Army's definition, like the howitzer pictured above.
Same with anti-tank missiles, MANPADS, etc. Where is the upper limit? What is not an arm per the Constitution?