The video above is of a M61 Vulcan, a six-barreled, air-cooled, electrically fired Gatling-style rotary cannon, which fires 20mm rounds at an extremely high rate of fire.
Now, imagine firing one of those rounds from a bolt action rifle. The Vulcan fires them at about 6,000 rpm, but the rare SSK Industries .950 JDJ rifle lets you shoot them one at a time.
The .950 JDJ is a modified, or rather converted version of the 20x110mm cannon rounds fired by the M61.
In the video below, the folks from Rock Island Auction Company in Illinois warm up with a 12 gauge, a 4-bore rifle, and then a .700 Nitro Express, before getting to the .950.
What practical purpose could a rifle like this have? Dinosaur hunting. Definitely dinosaur hunting.
Just take a look at that muzzle blast as it’s directed up and out by the considerable brake. Amazing.