Strange brass found at the range. What is it?

[Questor]

I found a case headstamped 5.7x28 at an indoor pistol range the other day. What kind of guns shoots this cartridge? No rifles are permitted at this range.  

The dimensions of the case include the inside diameter of the case mouth as 5.7mm, length as 28.8mm.  

Superficially it looks like a rimless 32 S&W necked down to .22 caliber.  The primer is of small size.

It appears to be military because the head stamp also has "04" on it, presumably year of manufacture. It also has what appears to be "FRB" or "TRB"

[ricciardelli]

What you have found is the 5.7x28...
It is made for the Belgium P90.
It is intended to replace the 9mm Parabellum.

Factory load is a 23 grain FMJ bullet @ around 2800 FPS.


(Yes the origina "5.6" post was a typo...)

[Questor]

Ricciardelli:

Are those typos? It really does say 5.7, not 5.6 on the headstamp. I don't think the bullet could be that light (I just have the empty case). The diameter is significantly larger than a .22. I would think it would be at least a 60 or 70 grain bullet, and probably heavier.

[Reed1911]

Actually,
It is the 5.7x28, not 5.6X28. The bullet available for Civilian use was the SS192 HP a 26g HP at 1800-1900 FPS. Due to FN bowing down to media hype (it quickly got dubbed the newest cop killer round) they switched to the SS196 a 40g Hornady V-Max at about 1100-1150FPS. While it is a neat little pistol to play with, the ammunition is just a little more powerful than the .22 Mag rimfire. Also available are a tracer round, Subsonic, and AP round. It was never intended to replace the 9x19.

[New Hampshire]

The round is also available in the FN Five Seven (a handgun)
Here is a link:
http://www.arizonagunrunners.com/Products/FNMfng/Five-seveN/pricing1five-seven.html
Brian M.