Remington’s Cannon: The MasterBlaster
The Remington MasterBlaster is a big suppressed 8 Gauge kiln gun.
The MasterBlaster system is the most productive and cost-efficient way to remove virtually any type of build-ups in boilers, kilns, silos, quarries or mines. Both the gun and the ammunition provide superior power, accuracy and dependability, shot after shot, at distances up to 300 feet
“Rapid Firing” 
nice
It fires special remington 8 gauge slugs weighing up to 3 oz. / 1312.5. 8 gauge has a caliber of 0.835″ / 21mm.
Zinc Build-Ups With Hard Exteriors and Soft Interiors
Perfect for self defense
More info here.
Methinks if it were loaded with shot instead of a slug, it would be perfect for duck hunting.:D
Except the Fed has declared the 8 gauge to be illegal for game hunting. And it’s been that way for quite some time now.