It's a brick. It's the world's first and perhaps only crew-served .45ACP. You have to be about seven feet tall and weigh 400 pounds to conceal carry it. When you run out of ammo you can use it as a battering weapon.
It is, the one, the only, the world's largest .45ACP semi-automatic handgun, I present, the HK MK23!!
Anyone use one before? Here's the link to the video:
Shooting the World's Largest .45ACP Semi-Automatic Handgun