Awhile back someone created a ridiculously impractical caliber the .950 JDJ. And a gun to shoot it out of: https://www.youtube.com/watch?v=xohy9gWz7kk. Needless to say, a rifle that has to have dead weight welded to it to make it even bench-shootable isn't very practical.
But I wonder if a better recoil management system might make it workable. For example, there's the GM6 Lynx, a shoulder-fireable semi-auto 50 BMG. And then there was the High Impulse Weapon system (https://www.youtube.com/watch?v=HyAl9qK3Rlg), a shoulder-fired 76mm grenade launcher/mortar. While that video still shows a hell of a lot of recoil, it was firing a fairly heavy projectile. For the same total muzzle energy, a smaller projectile- like the .950 jDJ?- would have less recoil.
So let's say one adapted a similarly robust recoil management system to the .950 JDJ. It would still be a novelty gun, but would it be something one could shoot with, as opposed to a bench queen?