P90 sighting

[frkelly74]

I think it was a P90. It was a bullpup receiver and a magazine that laid flat on the top of the receiver and the rounds were in crosswise and turned 90' to line up with the chamber and ejected out the bottom. Odd looking thing and it was in 5.7X28 FN caliber. The owner said he was having a really hard time finding ammo for it and couldn't even find bullets to reload. Is it an odd size bore? What Diameter would you need for it. He was firing into a 5 gal bucket with hardening 20 minute drywall mud in it and the hollow points did not show any signs of expansion when he recovered them. They also did not penetrate all the way through which I thought they might. they looked like 62 gr 5.56 bullets to me but i couldn't measure them. I have never seen one of those before.

[5.7 MAN]

the 5.7X28 is reloadable, however it very easy exceed recomended pressures with very small increments of powder. Data is available in the latest Lyman loading manual. Bullet Diameter is .224 and bullets up to 55 grns can be used.

The factory bullets are aluminium cored and very light at 28 grns, the are not designed to expand instead they tumble! There is a couple of other loadings on the market and the ammo has been scarce of late. The other two loads are a 40 grn hornady bullet and a 40 Grn FMJ.

A handgun is also available, I own one and it is probably one of my favorites!

[DCM]

As 5.7 said they are reloadable.
0.224" bullets
Western powders has data for them, RCBS has dies.

[scarry scarney]

When I did reload for it, Dillon did not have a conversion kit for the 550 for it. Over on the fiveseven forum board, I found a guy in the Vegas area that made a conversion kit for the dillon. I had the pistol, it would always throw the brass 10, 15 feet! It also always seemed to move the shoulder upon firing. And the brass seemed to have some kind of varnish on it that took forever to get of when tumbling. Not a fun cartridge to reload for, but back then, Ammo was hard to find.

[bootsnthejeep]

Not to mention it's so damn small! I though gas checking boolits was bad, I can't imagine trying to fat-finger a couple hundred of those dinky little cases thru my dillon, let alone a single stage.

Those guns are interesting, got to shoot one once, but the expense of the gun, the limited application, and the specialty ammo all spell three strikes for me. Pretty neat from an engineering standpoint, but if I want interesting engineering, I'll tear apart an old Merc outboard.

[Artful]

Yep, sounds like a FN P90 - full auto short barrel PDW
http://www.jeepgunner.com/p90.jpg

or maybe PS90 (civilian semi-auto only long barrel version)
http://blackcampbell.files.wordpress.com/2010/01/fiveseven.jpg

Seen here with FN's 5.7 handgun

5.7x28mm ammo sold in the US is without the penetrator bullets so depends upon speed to do the job.
http://upload.wikimedia.org/wikipedia/commons/thumb/1/12/57_size.jpg/538px-57_size.jpg
Case type Rimless, bottleneck [7]
Bullet diameter 5.7 mm (0.224 in) [7]
Neck diameter 6.35 mm (0.25 in) [8]
Shoulder diameter 7.9 mm (0.311 in) [8]
Base diameter 7.9 mm (0.311 in) [8]
Rim diameter 7.80 mm (0.307 in)
Rim thickness 1.14 mm (0.045 in) [8]
Case length 28.83 mm (1.135 in) [8]
Overall length 40.50 mm (1.594 in) [8]
Case capacity 0.90 cm³ (14 gr H2O)
Rifling twist 228.6 mm (1:9 in) [7]
Primer type Boxer Small Rifle [7]
Maximum pressure 345.0 MPa (50,040 psi)

[frkelly74]

Yep, that's the one,, with the longer barrel.

[JeffinNZ]

The swaging boys use the cases to make .308 cal projectiles.

Being a 'Stargate' fan I have a soft spot for the P90.