EmericD said:

I've got a very effective ammo lot of 7.62x51 mm DM151 (high density WC-Co core, MV around 880 m/s from a 22" test barrel @+52°C, and 855 m/s @+21°C) that will be tested against ceramic armor, but not before 2023. Against RHA, an exposed tip .277 Fury ADVAP (main hypothesis: a 32 mm long WC core, a MV of 3000 fps and a 0.29 C7) could probably defeat someting like 29-30 mm of RHA at 100 m, and 16-17 mm at 600 m which is (from my limited experience) the "entry ticket" to expect being able to defeat lvl IV ceramic armor. EDIT : with the above set of hypothesis, a .277 Fury ADVAP is duplicating the performance of the XM948 SLAP up to 500 m, and is slightly better after 500 m due to it's higher BC.

Very cool that you will be conducting ceramic testing; hoepfully you can report back but understand if you cant. 

Not sure which armor you will get to test. But the Iranian armor found in Ukraine, along with the various Level IV Chinese plates readily available on Aliexpress I think should be looked into as probable 'adversarial' systems. Adepts Colossus plate might be worth trying too as a harbinger for future advances in armor. 

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Thank you for doing the .277 ADVAP calculations; those are extremely impressive performance estimates. 

Based on your calculations, what do you expect that .277 ADVAP projectile would weigh? I imagine a good bit heavier than the steel/copper 6.8 'GP' EPR projectile?

how heavy is the steel core on 556 AP rounds?

smg762 said:

how heavy is the steel core on 556 AP rounds?

Which 5.56 mm AP round?

The P112?

>https://www.linkedin.com/feed/update/urn:li:activity:6986420763545239552/

From the T-Worx LinkedIn. They designed the powered rail system used in all NGSW applicants.

The point of particular note here, imo is the ammunition belt. Showing ostensibly the standard issue 6.8NGSW cartridge. The EPR bullet design is clear and expected. But the use of what appears to be an entirely steel case is very interesting.

Perhaps it turned out that SIG's multipart case design was too complex for mass military manufacture.

I initially thought that this would be lower-pressure practice ammo, but the EPR-style bullet confuses me.  My understanding was that practice ammo would use a bullet with less penetration and ricochet potential. 

I recall a NDIA presentation a number of years ago that discussed ammo weight reduction by utilizing thin-walled steel cases but had seen nothing since.  I wonder if the need for extra strength for the base of the new 6.8 cartridge has suddenly made steel cases much more attractive.

SIG's case design being particularly ridiculous was probably the biggest incentive Lake City needed to finally go through with it. 

Apsyda said:

The point of particular note here, imo is the ammunition belt. Showing ostensibly the standard issue 6.8NGSW cartridge. The EPR bullet design is clear and expected. But the use of what appears to be an entirely steel case is very interesting.

Perhaps it turned out that SIG's multipart case design was too complex for mass military manufacture.

It may be that the multi-part case proved too complex for mass production, but I would note that the T-Worx post does not say the rounds are the "standard issue" cartridge.

Another possible explanation for what appears to be steel cases is that they are dummy cartridges used for display at public exhibitions like AUSA 2022, instead of live ammo.

P.S.  Thank you for posting that photo.  I had wondered how the XM157 fire control could be mounted without interfering with opening the top cover. 

I see that the additional long rail clamps only to the short segment of rail on the top cover, so that the fire control and upper rail pivot with the cover.

Excellent find! 

Heres both images larger:

The cases to me look one-piece, and are black. 

Combined with this picture being taken at a display booth or office (where one generally doesn't want a belt fed machinegun with live ammo) I suspect these are polymer dummy cases with real EPR projectiles.

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In terms of EPR, its good to see they are nice and pointy and streamlined, which seems to my eye to match the 6.8 EPR prototype we had seen earlier.

gatnerd said:

The cases to me look one-piece, and are black.

Black?  Oh, great.  Now I'm going color blind.  The cases look gray to me.

gatnerd said:

Combined with this picture being taken at a display booth or office (where one generally doesn't want a belt fed machinegun with live ammo) I suspect these are polymer dummy cases with real EPR projectiles.

The T-Worx post said the photo was taken at AUSA 2022, so I agree that they are almost certainly dummy rounds.

However, they do not look like any polymer cases that I've seen.  They look to me more like lacquered steel cases.