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NGSW Phase 2 Consolidation and info   Small Arms <20mm

Started 30/8/19 by gatnerd; 501901 views.
stancrist

From: stancrist

26-Apr

You're welcome.  Glad I could help.

nincomp

From: nincomp

26-Apr

EmericD said:

Dimensions of the 6.8 mm GP according to the single picture available, probable error of 0.01" (1 pxl on the picture): BOAL: 1.41" Ogive: 0.825" Shank: 0.380" BT: 0.205" EDIT: those dimensions lead to a bullet mean density of 9.4 g/cm3, or a 120 gr bullet if the density is 8.4 g/cm3.

I have wondered if the NGSW trials actually used the bullet in the photo.  That is partly why I have been using the phrase "high-BC EPR-style bullet."  Do we know for certain that they used this particular bullet?

  • Edited 26 April 2022 2:03  by  nincomp
stancrist

From: stancrist

26-Apr

nincomp said:

I have wondered if the NGSW trials actually used the bullet in the photo.

I would think surrogate bullets were used in most testing:  https://youtu.be/5SGySgHP2wU?t=1

nincomp said:

Do we know for certain that they used this particular bullet?

Is there some reason to think this particular bullet is not the "government-provided" GP bullet?

Photo caption: 

Army’s 6.8mm GP Projectile compared to the Army’s current M80A1 EPR and the M855A1 EPR from an Army Futures Command event...  

Inside the Army's Quest for a Revolutionary New Bullet | Military.com

nincomp

From: nincomp

26-Apr

stancrist said:

Is there some reason to think this particular bullet is not the "government-provided" GP bullet?

I would just like verification.  It seems odd that another picture of the bullet has not appeared.  It also seems that the general consensus, at least on this forum, is that a steel-tipped EPR bullet should not be able to penetrate level 4 armor at distance, one of the stated goals of the program.

stancrist

From: stancrist

26-Apr

nincomp said:

I would just like verification.

The nearest I've seen to "verification" is the photo caption that I just added to my previous post.

nincomp said:

It seems odd that another picture of the bullet has not appeared.

Another photo of the same bullet would be pointless (No pun intended!), and tell us nothing new.

That being said, I'm surprised that there have been no photos of loaded rounds with the GP bullet.

nincomp said:

It also seems that the general consensus, at least on this forum, is that a steel-tipped EPR bullet should not be able to penetrate level 4 armor at distance, one of the stated goals of the program.

Well, since no one on this forum has tested the 6.8 GP ammo against Level IV armor, I'd classify that as speculation.

I also don't see how that consensus relates to the question of whether or not there is another GP bullet in existence.

EmericD

From: EmericD

26-Apr

stancrist said:

How many GAU-8 guns have been lost to burn thru of the aluminum case?

I have no idea, but in any case the number should be low enough than the risk / gain balance is considered good enough to continue using aluminum cases, even if the risk is there.

On the other hand, no one is using aluminum case for rifle ammo, even if the weight reduction is demonstrated, and significant amount of money was spent to try to develop such cases.

The balance of risk / gain is not good enough for small-arms application.

stancrist said:

If the neck separates from a cartridge case every one in a thousand rounds, I think most soldiers would consider that a rather serious flaw. I sure would.

I would also, and that's why we (and probably other armies around the world) didn't already ordered millions / billions of small-arms ammo with composite cases. The risk / balance gain should be evaluated for every system.

All in all, the situation found with composite case is not very different from steel case. Steel case are not really new, but even if steel case allows you a small weight reduction, a small capacity increase and reduction of expensive non-ferrous materials, you don't see a lot of countries replacing brass case ammo with steel case ammo.

EmericD

From: EmericD

26-Apr

nincomp said:

It would be interesting if they could do something like that and allow the ogive to be recessed in that false "neck" section. I had been thinking about that too. It would allow existing cartridges like 5.56x45 or 7.62.51 to use bullets with longer ogives. The trick would be to assure that the bullet stays supported and aligned with the bore and that the petals stay attached to the case.

I agree, and that's what I want to demonstrate with my "3rd Gen 5.56 mm".

In the absence of bullet support (a virtualy "no neck" brass case), I could launch a .208 C7 bullet at 900 m/s from a 20" barrel @300 MPa MAP (SD below 5 m/s) and print a 3.5 MoA, 10 shots group from a HK416 F rifle.

I think that even if the support of an array of plastic petals is not perfect, it will be a path in the right direction.

gatnerd

From: gatnerd

26-Apr

EmericD said:

EDIT: those dimensions lead to a bullet mean density of 9.4 g/cm3, or a 120 gr bullet if the density is 8.4 g/cm3.

Great info.

If the projectile is 120gr, what do estimate the g7 as?

Also if we're seeing 135gr @ 3000fps, then we'd expect this to hit 3100fps+...

EmericD

From: EmericD

26-Apr

nincomp said:

Do we know for certain that they used this particular bullet?

I had no confirmation that the bullet was this one.

In fact, some people on this forum already pointed out that the bullet in the picture can't be a 135 gr bullet with the current EPR configuration (copper core instead of bismuth core), and the bullet lacks a crimping groove.

So it could be a "spiral one" bullet, and the test 6.8 mm GP bullet could be different.

The SIG carbine is type classified as XM5, the SIG AR is type classified as XM250, but I saw no type classification for the 6.8 mm cartridge.

gatnerd

From: gatnerd

26-Apr

nincomp said:

It also seems that the general consensus, at least on this forum, is that a steel-tipped EPR bullet should not be able to penetrate level 4 armor at distance, one of the stated goals of the program.

There will be a GP and SP (special purpose) projectile that is presumably the tungsten load:

https://i.ibb.co/sKr7Y8R/original-1.jpg

"implement lessons from the XM1158 for the SP round"

https://i.ibb.co/jgYh1Nw/Screen-Shot-2022-04-26-at-4-08-02-AM.png

from earlier in this thread:

http://forums.delphiforums.com/autogun/messages/7519/291

  • Edited 26 April 2022 4:41  by  gatnerd
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