The .950 JDJ is the biggest rifle round to receive a "Sporting Use Exception" (no explanation given as to what that exception is) in the United States. They can be owned by a citizen over the age of 18 that complies with all Title I regulations (Basically like buying a centerfire hunting rifle).

Projectiles for the round have to be custom made by the designer(SSK industries), has a weight around 1/2lb and has a cost of about 40 USD.

The muzzle energy is 38,685 ft/lbs (ouch)

The velocity ranks around 2.200ft/second

The rifles that fire the round weighs approximately 85lbs with a starting cost of 8,000 USD.

As of 2017, only 3 rifles were produced and SSK industries will no longer manufacture the ammunition.

More Info: en.wikipedia.org