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Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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Improved five seven   General Military Discussion

Started 24-Mar by smg762; 1456 views.
smg762

From: smg762

24-Mar

The five seven and P90 share ammo, but can't share clips. Clearly a P90 mag wouldn't fit a pistol.

I wondered if you could mod the P90 so that instead of the ammo being turned 90degrees by the magazine, it simply takes a regular five seven mag.

However you place the mag flat on top of the P90, and the rounds enter a 'turret' on the gun, which turns them 90degrees. The tricky part is the ammo making the jump from magazine into the turret.

Clearly the mags, pistol, and P90 would get a big redesign.

The benefit is shared clips, and you can still use big 40round mags. Any comments as to whether this would be technically possible?

It could work with a scratch built 556 gun, allowing a 40round mag which still let's you shoot prone.

In reply toRe: msg 1
stancrist

From: stancrist

24-Mar

smg762 said:

Clearly a P90 mag wouldn't fit a pistol.

Clearly you're mistaken.  https://youtu.be/S0SteWIw6PU?t=3

smg762

From: smg762

24-Mar

P50 is huge. My idea would allow 30-50rnd mags in both five seven and P90. And easy prone shooting

But I'd like to know if people think it would work. 

I'm trying to think how the ammo could make the jump to the rotating device.

In reply toRe: msg 3
stancrist

From: stancrist

24-Mar

Does not look feasible to me.

If I understand correctly, you want the Five-seveN mag to be longitudinal atop the P90.  I think that would require a very complicated mechanism. 

Not only do the cartridges have to transfer from the mag to the rotating turret, they have to change direction after being stripped out of the mag.

Refleks

From: Refleks

24-Mar

You could design it to accept a pistol mag up the ejection chute, or a P90 mag from the top, but then you'd have to decide what to do with the spent casings (particularly when feeding from below).  

If you want to be able to use either feeding approach without changing out the internals, you're stuck designing it to eject out of the side, and half the point of the P90 was that it was ambi.  I guess you could design it to forward eject like the RFB,  but that brings up other issues such as the annoying tinkle of built up casings hitting the floor at an inopportune time, like when you're about to go through a fatal funnel 

  • Edited 24 March 2021 18:32  by  Refleks
In reply toRe: msg 1
roguetechie

From: roguetechie

25-Mar

Yes it could be done but it shouldn't be.

The gun the p90 is based on basically does this actually.

As you can see it's been done but that doesn't mean it's a good idea, especially if you're going to try to make the pistol and smg mag interchangeable.

stancrist

From: stancrist

25-Mar

RT, you're mistaken.  It has not been done in the weapons which you have pictured..

The Marshal Arms PDW used a special magazine developed specifically for that gun.

What smg762 wants is to use standard Five-seveN pistol magazines in the P90 SMG.

smg762

From: smg762

25-Mar

no. the mags and all guns would be heavily modified. the hard part is making the jump from mag to P90 rotating chamber. im just wondering if its even physically possible

Ejection would be downward. P90 mags have the turret as part of the mag. I'm just proposing that the turret is part of the gun. 

The hill smg from the 60s used this exact mechanism...lots of Google articles..

And what about a 556 model with 40rnd mags that let's you shoot prone

  • Edited 25 March 2021 8:25  by  smg762
In reply toRe: msg 8
stancrist

From: stancrist

25-Mar

smg762 said:

no. the mags and all guns would be heavily modified.

That is not what you said in the OP:  "I wondered if you could mod the P90 so that instead of the ammo being turned 90degrees by the magazine, it simply takes a regular five seven mag."

smg762 said:

the hard part is making the jump from mag to P90 rotating chamber. im just wondering if its even physically possible Ejection would be downward. P90 mags have the turret as part of the mag. I'm just proposing that the turret is part of the gun.  The hill smg from the 60s used this exact mechanism...lots of Google articles.

The Hill SMG --  like the Marshal Arms PDW -- used a magazine designed for that weapon's feed turret.  I would think that with an appropriately-configured magazine and feed system, it should be possible to modify the P90 as you desire.  However, I very much doubt that the new magazine would work in the Five-seveN pistol.

smg762 said:

And what about a 556 model with 40rnd mags that let's you shoot prone

Seems impractical.  40-rd 5.56 mags are curved.  A straight mag is needed.

Mustrakrakis

From: Mustrakrakis

25-Mar

smg762 said:

im just wondering if its even physically possible

Almost anything is possible if someone is willing to throw enough people and money at the problem.  You'd probably be looking at fairly substantial redesign of the P90 in order to make it possible though...enough so that it might make more sense to start over with a new design entirely.  Of course, at that point you'd want to ask yourself, "Why would I want to spend a significant amount of effort to make a PDW that already took large PDW magazines also take smaller proprietary pistol magazines, when the whole point of a PDW is to carry it instead of a pistol?"

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