5000 fps...and if so...why?

[MachIVshooter]

Didn't the old Remington .17 get real close to 5k?

4,400-4,500 is about it.

The .17 Rem, .204 Ruger, .223 WSSM and .220 Swift are the fastest commercial rounds out there, running 4,000-4,500, depending on bullet weight and barrel length. Anything faster is so overbore that throat life is in the hundreds at best. A few wildcats and a couple of the Lazzeroni cartridges can push light-for-caliber bullets to ridiculous velocities as well, but still quite a bit short of 5,000.

The .22 Eargesplitten Loudenboomer (yes, it's real) hit 4,800, IIRC.

Weatherby did push over 5,000 with the .30-378 using custom 60 grain bullets.

.50 BMG firing .308 bullets in sabots have also been pushed to 5,200.

These and other such hyper-velocity attempts require very long barrels to achieve their numbers.

There just comes a point when all you're really doing is burning more powder, increasing chamber pressures and turning the throat into vapor.

 

[fireman 9731]

Haha no, I think its a real picture, and I think the 50-17 wildcat is real. More of a novelty than anything. In the picture it looks the case has a spent primer in it. I have seen other pictures though besides that one.

 

[Flopsweat]

The 120mm tank gun attains a velocity of 5,500 fps using the APFSDS-T round. There is no metal cartridge case; just a stub base with primer.

http://www.inetres.com/gp/military/cv/weapon/M256.html

OT, but they make a giant buckshot round in this caliber. Near the bottom of the page:

The 120mm M1028 Canister is a muzzle action anti-personnel tank cartridge. This cartridge is fired from the 120mm main gun of the M1A1/M1A2 Abrams tank and is effective at ranges less than 700 meters. The baseline design utilizes a payload of approximately 1,100 tungsten balls that are expelled from the projectile casing upon muzzle exit, similar to a shotgun shell.

Unlike previous antipersonnel cartridges, the M1028 does not have a fuze; it is intended to be a low-cost, low-technology cartridge.

The M1028 uses a combustible cartridge case and propulsion-ignition system common to the current 120mm tank ammunition.

This is a training standard item used in both training and combat.

Type Classification Date: December 2004. Unit cost: $2,000 (Fiscal Year 2009).
¦Length: 30.67 in (779 mm)
¦Weight: 50.51 lb (22.9 kg)
¦Projectile Color: Olive drab with white markings.

Yowza. They do not list a muzzle velocity, but with a 700m range, it's got to be bookin'.

 

[CB900F]

Fella's;

If I remember correctly, the American Rifleman published an article within the last ten years or so on the government experimental hyper-velocity guns. And, as was stated previously, the purpose is to simulate satellite impacts with either space debris or as a target.

900F

 

[brickeyee]

The article is from 1994 .....

Light gas guns predate even 1994.

 

[MCMXI]

A large caliber sabot can be used to propel a smaller caliber bullet at 5,000+ fps with existing powders. It'd be interesting to play with a .338 LM sabot and shoot an 80gr .223 bullet out of the muzzle at 5,500 fps. It'd probably need to be a solid bullet or at least bonded to keep the jacket on ... but maybe not.