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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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PDW again   Small Arms <20mm

Started 20/12/20 by DavidPawley; 42219 views.
stancrist

From: stancrist

10/2/21

graylion said:

I assume you agree on mag on top of action/barrel, not the other way 'round?

Yes.

graylion said:

I am going to postulate a folding down front grip.

Okay.

graylion said:

Action. Now here are a bucketload of options:

1. simple blowback

2. delayed blowback

3. gas/piston

personally I lean towards delayed blowback, specifically roller delayed. simple blowback won't handle this kind of powerful cartridge. Gas is just too complex and clumsy for the gun design we are envisioning.

Kind of action:

1. normal

2. Boberg

Boberg would give us more useable barrel length, can it be made reliable enough?

This will likely be a rather rough cartridge. Can we do something to make shooting it less unpleasant like eg an integrated suppressor?

Not an area in which I have knowledge.  Suppressor does not appear to reduce recoil in this video:  https://youtu.be/qY-IuDabD3Q?t=5

graylion said:

I am also thinking that we might want to have a 4 way selector and a burst mode, given the fact that with these troups we can probably not rely on proper trigger control

Okay, although I think that likely does not matter.  Any armies which were to adopt it, might very well specify a different selector pattern.

stancrist

From: stancrist

10/2/21

smg762 said:

I am sure something like 6.5 CBJ would work best. from 12' barrels it can group 13 inches at 300m. Is that reasonably good?

I don't know that I'd call it "reasonably good", but it's perhaps good enough to be usable.  Doesn't seem like any armies like 6.5 CBJ enough to adopt it, however.

  • Edited 11 February 2021 0:38  by  stancrist
graylion

From: graylion

11/2/21

stancrist said:

Not an area in which I have knowledge. Suppressor does not appear to reduce recoil in this video: https://youtu.be/qY-IuDabD3Q?t=5

They do because of gas expansion, see here https://youtu.be/h4ESNfY1SuU

I think there should be some solid amount of expansion space next to the barrel, but even an integrated suppressor is making the gun longer, so I think we can forgo that. Muzzle brakes also make the gun longer and they increase the noise for the guys who are fighting next to you. We may have to simply not use any of this. Bang is actually not too bad (like a heavy handgun, less than a 5.7 handgun) and recoil is somewhere along the lines of 5.56x45. Would that be OK with our frame?

I am going to postulate the Boberg principle since it basically shortens the gun by a full cartridge length. Roller delay and closed bolt affect reliability and precision, Same mechanism as MP5 and G3, so I'd like these 2. I could not find anything about the Boberg principle being unreliable, OTOH it has never been used for full auto before. Given that the PDW replacement is not urgent, the Elbonian Office for Arms Procurement decides on an extended trial.

  • Edited 11 February 2021 9:03  by  graylion
stancrist

From: stancrist

11/2/21

graylion said:

I think there should be some solid amount of expansion space next to the barrel, but even an integrated suppressor is making the gun longer, so I think we can forgo that. Muzzle brakes also make the gun longer and they increase the noise for the guys who are fighting next to you. We may have to simply not use any of this. Bang is actually not too bad (like a heavy handgun, less than a 5.7 handgun) and recoil is somewhere along the lines of 5.56x45. Would that be OK with our frame?

Seems reasonable to me.

graylion

From: graylion

11/2/21

After lots of chinwagging the Elbonian Army Staff decided to go with the Boberg loading principle, but commissions a second, conventional design to mitigate the risk of failure. It is also agreed to specify a red dot sight as standard.

This would appear the gun mostly done, am I missing anything?

stancrist

From: stancrist

11/2/21

Nothing else comes to mind.

graylion

From: graylion

12/2/21

So, to summarise:

  • looks like a giant pistol
  • Magazine is P90 style and on top
  • telescoping shoulder stock
  • Boberg "bullpup" operating mechanism
  • closed bolt (open bolt is not really feasible with Boberg operation)
  • roller delayed blowback
  • red dot sight
  • skeleton holster or sling (I am trying to imagine the commentary if somebody chooses to carry it in an appendix carry)
  • 4 way selector for burst mode

Just occurred to me what rate of fire? 800 rpm? Slower? Faster?

stancrist

From: stancrist

12/2/21

graylion said:

what rate of fire? 800 rpm? Slower? Faster?

Yes, definitely one of those.   ;^)

graylion

From: graylion

12/2/21

stancrist said:

graylion said: what rate of fire? 800 rpm? Slower? Faster? Yes, definitely one of those.   ;^)

766 it is so ;o)

  • Edited 12 February 2021 21:12  by  graylion
In reply toRe: msg 250
graylion

From: graylion

13/2/21

graylion said:

looks like a giant pistol Magazine is P90 style and on top telescoping shoulder stock Boberg "bullpup" operating mechanism closed bolt (open bolt is not really feasible with Boberg operation) roller delayed blowback red dot sight skeleton holster or sling (I am trying to imagine the commentary if somebody chooses to carry it in an appendix carry) 4 way selector for burst mode

The Boberg mechanism increases the barrel length by a cartridge length, so we are looking at a 11" barrel length

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