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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; 123808 views.
schnuersi

From: schnuersi

24-Sep

Well the XM5 might be a carbine for .30 cal or full power rifles but its size and weight is not in the same class as the common 5,56 carbines.
With the supressor fitted, which seems to be the intended way of use, the XM5 is about the size and weight of a G3 battle rifle.
Its so large and heavy that its completly unsuitable as PDW or secondary weapon.

stancrist said:

I am only saying that if the small arms used by infantry riflemen and machine gunners can defeat modern hard body armor, then it seems to me that a future PDW should also penetrate the same armor (except at much shorter range).

IMHO that depends if this is a realistic goal.
From my point of view for a PDW carryability is the primary concern. Followed by usability. If such a level of penetration at 100 m is possible without compromising the carry- and usability that is fine.

schnuersi

From: schnuersi

24-Sep

stancrist said:

9mm has also proven quite effective in similar mass shootings, so if that's the basis for pistol caliber there is no reason to change.

Yes but 5.7 has less recoil, flatter trajectory and larger capacity magazines. Which makes it the better choice.

schnuersi

From: schnuersi

24-Sep

graylion said:

I am uncertain about the carbine - who gets it? HE slingers and machine gunners? Snipers?

I think the guys who are concerned should figure that out by themself.
If they want a PDW give it to them. Same with carbine or pistol.

Personally I don't think machine gunners need a secondary weapon at all. They have a machine gun.

In reply toRe: msg 696
graylion

From: graylion

24-Sep

graylion said:

I have been playing with a cartridge that would kind of do the job on defeating Lvl IV armour out to 100m, But a pistol cartridge it ain't. A carbine catridge sister to the .277 Fury? Yes. This thing will not fit into a handgrip unless it is a single stack, so P90 style mags it is, even for the pistol :( Bullet Aluminium with steel core: http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=mm.&weight_unit=grains&bullet_name=GLS+PDW+II&re_calculate=yes&boundary_layer=L%2FT&entry=return&diameter=7.51&length=21&nose=14&meplat=0&drive_band=7.8&base_diameter=5&angle=8.5&boat_tail=5&secant_radius=5.7&weight=49.2&density=5.2 And, assuming our PDW has a 200mm barrel, I get this (assuming same pressure as military load for .277 Fury).  Google Docs 7.5 Graylion Load R24.png Read more from Google Docs

Recoil energy is 8J, that's about equivalent to .40 S&W

schnuersi

From: schnuersi

24-Sep

autogun said:

If you want to maximise penetration above all else in a pistol/PDW, then see the 6.5mm CBJ.

With this one IMHO its more about the projectile.
But something like this based on or in the power range of the 7,5 BRNO might deliver the desired penetration.

I am also curious how a saboted penetrator like the one of the 6.5 CBJ but fired from a 5.7x28 or 4,6x30 would perform.

stancrist

From: stancrist

24-Sep

graylion said:

       stancrist said: 9mm has also proven quite effective in similar mass shootings, so if that's the basis for pistol caliber there is no reason to change.

Not my point. I was attacking the statement that "nobody wants a pistol in 5.7"

Sorry, I was imprecise.  I did not mean literally "nobody" wants a 5.7mm pistol.  I meant that no army wants to switch from 9mm pistols to 5.7mm pistols.

graylion said:

       stancrist said: The US Army apparently does not share your opinion, because the XM5 "rifle" with its 13-inch barrel is, at best, really just a carbine, if not actually in the SBR class.

And yet it is 3" longer (36") than an M4 - so I am calling BS.

How is it BS?  SBR = Short Barrel Rifle, not Short Overall Length Rifle.

The M4 carbine has a 14.5" barrel.  The XM5 rifle has a 13.0" barrel.

graylion

From: graylion

24-Sep

stancrist said:

How is it BS?  SBR = Short Barrel Rifle, not Short Overall Length Rifle. The M4 carbine has a 14.5" barrel.  The XM5 rifle has a 13.0" barrel.

Cos it is missing the point - carriability

stancrist

From: stancrist

24-Sep

schnuersi said:

Well the XM5 might be a carbine for .30 cal or full power rifles...

Well, the 6.8 is a full-power cartridge.

schnuersi said:

...but its size and weight is not in the same class as the common 5,56 carbines.

The XM5 is certainly heavier than the M4, but overall length is about the same (~30 inches with stock retracted).

schnuersi said:

Its so large and heavy that its completly unsuitable as PDW or secondary weapon.

I agree.  However, the Swedes apparently think an 8.4-lb rifle is suitable for use as a PDW or secondary weapon.  grin

  • Edited 24 September 2022 22:34  by  stancrist
stancrist

From: stancrist

24-Sep

schnuersi said:

5.7 has less recoil, flatter trajectory and larger capacity magazines. Which makes it the better choice.

Less recoil would help, but the flatter trajectory won't make a bit of difference for most soldiers.

And we're looking at 20-rd mags for the FN 5.7 pistol versus 17-rd mags for the 9mm M17 pistol.

The hard truth is that 5.7 is just not enough better to justify the change.

Especially seeing as how pistols are "almost useless" in military combat.  relaxed

  • Edited 03 October 2022 20:51  by  stancrist
stancrist

From: stancrist

24-Sep

schnuersi said:

I am also curious how a saboted penetrator like the one of the 6.5 CBJ but fired from a 5.7x28 or 4,6x30 would perform.

That seems somewhat less than feasible. 

6.5 CBJ penetrator is only 4mm diameter.

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