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NGSW Phase 2 Consolidation and info   Small Arms <20mm

Started 30/8/19 by gatnerd; 549281 views.
EmericD

From: EmericD

26/4/22

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

26/4/22

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

26/4/22

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

26/4/22

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

26/4/22

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
stancrist

From: stancrist

26/4/22

gatnerd said:

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

"implement lessons from the XM1158 for the SP round"

The XM1158 is the Advanced Armor Piercing (ADVAP) round.  So logically, the GP projectile would not likely ever have been expected to penetrate Level IV armor at distance.

gatnerd

From: gatnerd

26/4/22

Correct on Level IV.

M80A1 can defeat 'Level III+' ceramic armor designed to stop M855 and 7.62 M80 @ 2800fps impact velocity though. 

Can the Army's new 7.62x51mm EPR ammo defeat composite armor?

The Army's new 7.62x51mm M80A1 enhanced performance round versus Spartan Armor Systems 3610GL composite level III+ plate. Note: this plate is not designed no...

Level III+ is analogous to Russias 6B45 level armor; I'm not sure if that is their standard issue or not. 

https://www.reddit.com/r/tacticalgear/comments/miv7jb/6b45_granit_gost_5a6a_russian_body_armor/

It will also be able to piece DIY steel armor like we've seen being used by the Ukrainians, and could probably expect to see improvised elsewhere. 

M80A1 vs AR500 Level III

This is the first M80A1 body armor test so far, this is the 130gr lead free EPR 7.62 NATO round vs a steel Level III body armor plate from AR500armor.comYou...

  • Edited 26 April 2022 6:01  by  gatnerd
stancrist

From: stancrist

26/4/22

EmericD said:

...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.

It could be different.  Or it could be the test bullet is the same as in the photo.

AFAIK, there is nothing which says the GP bullet necessarily weighs 135 grains.

It's more likely that the 135 gr surrogate duplicates the weight of the SP bullet.  

If the GP and SP bullets have the same dimensions, the GP would weigh less.

And I wouldn't read anything into the lack of a cannelure other than that the bullet may have been designed for CT ammo, which does not need a cannelure, and which -- until the news leak about Textron dropping out of the competition -- some here thought was the Army's preferred (or hoped for?) solution.

Notice that photos presented by the Army (see below and post #2589) show bullets that do not have cannelures.

EmericD

From: EmericD

26/4/22

stancrist said:

AFAIK, there is nothing which says the GP bullet necessarily weighs 135 grains.

Absolutely.

The only clues we have are that:

  • the bullet in the picture should be lighter than 135 gr with the current EPR construction, but this weight could probably be achieved using the original bismuth-core EPR,
  • at least 2 competitors (True Velocity and PCP tactical) used outsourced 135 - 136 gr solid copper bullets for their in-house development phase.
gatnerd

From: gatnerd

26/4/22

EmericD said:

at least 2 competitors (True Velocity and PCP tactical) used outsourced 135 - 136 gr solid copper bullets for their in-house development phase

We also have Soldier Systems initial reporting on the SIG's specs, which quoted 135gr @ 2850fps 13", 3000fps 16". So thats our 3rd indication of 135gr being relevant.

The Cobalt / MARS offering was a 140gr @ 3200fps, which as far a I know is the exception. But that could be simply the round they showed to a gun mag after they were not selected. 

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