5.7x28mm Ammo Ballistics in a Pistol

Isher2000

Has anyone see a source of ballistic information on the various cartridge types loaded for the FN 5.7x28mm cartridge.

I'd like to find information on the relative velocity and muzzle energy of the:

SS190 AP cartidge (Miltary/LEO)

SS192 28gr. High Velocity (Now Military/LEO, existing stock civilian legal)

SS195LF 28gr. Medium Velocity (Unrestricted)

SS197SR 40gr. V-Max (Unrestricted)

SS198LF 28gr. High Velocity (Military/LEO)

I'm interested in the degree to which the various loading have been slowed down from the original SS190 AP loading and how much impact the slightly different bullet contructions may have.

Any direct knowledge out there or does anyone know of a valid public published information source?

Like the early supporters of the 5.56mm M-16 with slow twist barrels, 5.7x28mm supporters claim good performance through a combination of hydrostatic shock and bullet tumbling. The 5.56mm in the slow twist barrels actually delivered on some of the hype. I'm not so sure about the 5.7x28 at substantially lower velocities.

Of course that didn't prevent me from buying a Five-seveN to play around with so I can see for myself. :-)

leeblackman

"supporters claim good performance through a combination of hydrostatic shock and bullet tumbling"

They probably mean within terminal ballistics right? I don't think anyone would support a bullet tumbling in flight... But that has more to do with bullet design, not barrel twist rate, even though barrel twist rate would effect nutation which would increase probability of tumbling after impact. But alot of nutation would also mean that the twist rate is not optimal for the bullet, which sacrifices accuracy, sometimes excessively?

Am I wong?

leeblackman

I mean bullet design effecting terminal ballistic not in flight tumbling BTW.

Didn't the spanish or someone experiment with a bullet that had a spoon nose or something? I know the soviets used a hollow cavity in their 5.45x39mm to make it tumble when it impacted.

What all factors effect a bullet as far as tumbling once it enters a body?

ripley16

Here is some info.
http://www.brassfetcher.com/5.7x28mm.html

Isher2000

Yes, sorry I was unclear. I'm talking about tumbling that occurs once the bullet has entered the target medium.

The old M16 story was that the 1 in 12 twist rate of the original issue M16 was just enough to stabilize the 55 gr. bullet out to normal engagement ranges. When the bullet struck it was supposed to be just wobbly enough to start to tumble and fragment.

The newer 62 gr. bullet and faster 1 in 7 twist barrel was partly adopted because of some work done by Sweden, I believe, that showed that the heavier, better stablized bullet was more likely to drill straight thru and minimize wounding to a "civilized" level. The other stated benefits of more effective range and penetration of helmets and body armor were the other reasons given for the change.

I've read that our military sort or confirmed some of this during the street fighting in Mogadishu not too long a go. The new issue 62 gr., penetrator bullets fired in the current 1 in 7 twist barrels did just what was expected. The punched nice neat holes in the opposition without always inconveniencing them enough to stop their attacks. Unfortunately the poor civilized European allies that pushed for the adoption of the more heavily constructed 62 gr. bullet in a 1 in 7 twist barrel did not get the final desired result. It seems the old 55 gr. bullets spun at a much faster rate than they were designed for tended to break up on impact creating wider "uncivilized" wound tracks and quick stops on the opposition. Our guys switched to the old style ammo and were able to get the job done more effectively.

Whew sorry for the run away switch in topic there. I kind of doubt the 5.7x28 is going to do anything quite so impressive at velocities running somewhere between 1700 to 2200 FPS depending on the ammo involved. Sounds more like your father's .22 Hornet territory. :-)

quote:Originally posted by leeblackman
"supporters claim good performance through a combination of hydrostatic shock and bullet tumbling"

They probably mean within terminal ballistics right? I don't think anyone would support a bullet tumbling in flight... But that has more to do with bullet design, not barrel twist rate, even though barrel twist rate would effect nutation which would increase probability of tumbling after impact. But alot of nutation would also mean that the twist rate is not optimal for the bullet, which sacrifices accuracy, sometimes excessively?

Am I wong?

Isher2000

That is a great web site.

That's exactly what I was looking for.

Now if they'd just test some of the faster moving SS192 & SS198 that's still out there and some of the military issue SS190 to provide a comparison to how the cartridge was intended to work before it was kind of "neutered" to prevent politically incorrect over penetration. :-)

Thanks

P.S. - This isn't strickly academic. I do know a gun shop clerk that wears a Five-seveN loaded with SS192 when he's behind the counter because he's convinced that is is a good defensive round that minimizes over-penetration. Hmmm...

P.P.S. - There a couple of interesting web sites on the Five-seven and the 5.7x28 mm cartridge.

http://fivesevenforum.net/index.php

http://www.fnforum.net/

quote:Originally posted by ripley16
Here is some info.
http://www.brassfetcher.com/5.7x28mm.html