Firearms and Ballistics expert, Writer, Cars and apparently too nice for my age
Well that, my friend, happens to be a nifty round called the .220 Swift
The Swift, created back in 1935 by Remington, is an extremely effective cartridge that consistently hits speeds above 4000 f/ps. Its fastest recorded ever was at about 4665 f/ps. The round itself is an amazing feat of ballistics design, as it allows Rifles chambered in the round to have near dead-on, point and shoot accuracy with virtually no bullet drop on smaller game up to 375 yards out.
Its so effective, in fact, that the hydrostatic shock it gives off upon impact is capable of taking out even larger game in the deer hunting community - but is usually only legal to use as a varminter, or against smaller deer like Roe.
The closest equivalent cartridge ever made, specifically to try and trump the Swift, is known as;
The Eargesplitten Loudenboomer
That’s basically a Weatherby .378 necked down to .224 calibre. And it only achieved 4604 f/ps. Ridiculous, right?
Anything for a world record though.
8 years military, 23 years law enforcement, firearms Inst.
Well I guess if your open in your interpretation of “ bullet” then I would have to go with the light gas gun. It used a smokeless powder change to send a piston down a tube that is filled with high pressure hydrogen gas compressing it even more. The end of the tube has a rupture disk that has been calibrated to rupture at a specific pressure so it acts as a valve.
The hydrogen is then pushed by the piston through an even smaller opening at the end that accelerates the gas even more. This launches the projectile at up to 8 km/s or 26,246 fps. That would be Mach 23.5.