.50-20mm wildcat cartridge idea? Discuss

[Rachen]

Many cartridges like the .17 HMR/HM2 are wildcats built by necking down the cases of established magnum cartridges, in this case the .22 Mag.

What if one was to neck down a standard 20mm casing to accept a .50 BMG FMJ or tracer slug, using standard 20mm propellant charge.

Discuss this concept. What would be the resulting velocities, muzzle energies, and the rifles which must be built to chamber this new, hypothetical wildcat round: The .50-20mm

 

[jgcoastie]

Already been thought up, produced, and sold.

http://www.anzioironworks.com/Anzio-20-50.html

 

[BPowderkeg]

long, long ago i read an article where a ballistics crew necked down a .50 BMG to an old phonograph needle, the velocity was somewhere in the 5,000 FPS range, it was a smooth bore if i recall.