Look closer. That's my 22 cal next to the A-10 Warthog 30mm practice round. Would almost seem surreal if I didn't know any better from growing up in the military.
And the gun part, the business end that ejects the 30mm round out. If you are old as I am, you may remember the ad that was produced from the photo below. A flying machine specifically built around the weapon itself. All 4200 rounds/min! Thanks Dad!