[fester225]

Does anybody know of a good online description of how a P90 magazine works?

 

[ick]

it is magic

 

[M1P90]

It works like any other mag but at the end the bullet rotates 90 degrees up a ramp so it is in line with the barrel. I'm sure there is a video around here somewhere that shows this.

 

[ShipWreck]

There is some info here:

http://en.wikipedia.org/wiki/FN_P90

 

[QB 45]

I wonder what the purpose of the short-recoiling barrel is.

Also, I didn't know P90's had binary triggers.

 

[DAUG]

What's a binary trigger??? :-?

 

[Promoted Pawn]

I wonder what the purpose of the short-recoiling barrel is.
...

It's so the bullet can exit before the case is drawn out of the chamber. The pressure of the case keeps it in the chamber until the end of the short recoil stroke.

 

[Promoted Pawn]

What's a binary trigger??? :-?

when the selector is on A you squeeze a bit for a single shot, or all the way for full auto
the AUG and F2000 are the same way
...and yes the PS90 mags are magical.

 

[JadeRaven]

It seems like it'd be awfully prone to failures. . . so it must be magic.

 

[fester225]

OK, so it's magic

Now that we've all agreed the P90 magazine is magic, does anyone have a magazine with a patent number on it?

 

[DAUG]

I don't know . . . and can't verify, since I'm at work. Just curious why that would be important?

 

[Texas Armadillo]

They're not magic!

Jeannie makes them work!

 

[Promoted Pawn]

no patent number on my mags.
I can give you some more details as to how it works.

The double stack encounters a wall. At the base of the wall is a hole that allows one round at a time. Because of the slope of the wall and the spring pressure a round will move smoothly into this hole on each cycle.

So now we have a round in the hole. It sits below the level of the double stack but is oriented the same way.

On the next cycle this round in the hole encounters a smooth ramp. The shape of the ramp causes the round to rotate 90*, pivoting near the middle. The geometry and materials are such that there is very little friction.

On the next cycle this round we have been following will be stripped from the mag and fed into the chamber.

There are two plastic rollers in the mag that serve to push the last rounds (number 49 and 50) through the hole and ramp. These plastic rollers are shaped so they can't come out like the ammo does. (they stop halfway up the ramp)

 

[Zhurdan]

Not to be too nitpicky, but the rounds make two 45 degree turns up the ramp. The round ready to be chambered is in line with the bore, the next round is on the ramp at a 45 degree angle, and the third round is at 90 degrees to the bore axis. Then they proceed to go to double stack configuration on top of the two dummy rounds as you described. I have some video of it somewhere, because someone else asked me about it. I'll try and find it.

Zhur

 

[WildRice]

Before I bought my PS90 I assumed the disc-like structure at the rear end of the magazine somehow rotated to turn the rounds into the feed position. However, I found that it was just a simple, helical, curved ramp with no extra moving parts. There are two rollers, but they just simulate rounds and assist pushing the real rounds.

So it is not some delicate rotating mechanism, just a helical ramp that does not move or break. It is very reliable and quite ingenious. It allows a very high ammo capacity without adding to the profile of the gun.

 

[Promoted Pawn]

Not to be too nitpicky, but the rounds make two 45 degree turns up the ramp. The round ready to be chambered is in line with the bore, the next round is on the ramp at a 45 degree angle, and the third round is at 90 degrees to the bore axis. Then they proceed to go to double stack configuration on top of the two dummy rounds as you described. I have some video of it somewhere, because someone else asked me about it. I'll try and find it.

Zhur

I remember hearing that too. But it's not true. The round turns 90 degrees in a single cycle.