600 Nitro Express.
A 900-grain bullet at 1950 fps will yield 7600 ft. lbs. of energy and 154 ft. lbs. of recoil.
Ammunition is somewhat available
The 600 Nitro Express is not (if you can believe it) the biggest kid on the block. I am stopping here because the others are too hard to find and therefore not practical as hunting cartridges. The 600 in either length (2.8” or 3”) was the largest of the British elephant cartridges until 19881. They were both introduced by Jeffery before 19011. This is one powerful cartridge and it fires a very large bullet. If you do not believe me, grab a ruler and imagine a slug .6 inches wide and about an inch long. It is huge. While a famous cartridge, in actuality, there were never that many rifles made for it. It is simply too overpowered for anything except a very angry elephant or buffalo at a distance closer than up close and personal. The recoil is beyond severe and I’d imagine downright unpleasant to shoot.
A 600 Nitro Express beside a .223. Photo from huntforever.wordpress.com
