EmericD said:

Anyway, congratulations to the US Amy for selecting the .276 Pedersen as its new service cartridge, 90 years after its first rejection!

Actually, the .276 Pedersen was a 7mm cartridge, not 6.8mm.

However, the Chinese were 115 years ahead of the US Army.

6.8x57 Chinese Mauser

EmericD said:

This "low recoil & practice" 6.8x51 mm fired from the M5 is delivering as much impact energy above 500 m as the 7.62 mm M80 fired from a M14, with 40% less impulse.

So, that could explain...why SOCOM resumed it's 6.5 mm CM program.

I don't follow.  How does it explain why SOCOM resumed work on the 6.5 CM program?

The 6mm Lee cartridge will rise again!

I think it's a pity that 6mm Navy didn't get perfected and adopted by the Army, too.

Imagine how much different the evolution of US military small arms might've been.

6mm Lee Navy - What If? by Nolo84 on DeviantArt

I concur on the problems derived from emission, but certain technologies can be at the same time reliable and not detectable beyond, say, 20m

If you get the display part of the FCS system outside of the FCS in a modular way, then it could be served on a helmet. Maybe 200-300 grams could be saved, I'm not sure.

I'm aware that it is not doable on the short term. But beyond that, weight savings are going to be decissive

I guess that the absence of a electronic trigger is already a bottleneck. A second one would be the pairing with external sensors that provide target detection and collaborate with the firing solution.

OTOH there is a difference between an aware and unaware moving target. The former will risk as less as possible, and thus the best that it can be done is to supress them with close supressive fire.

And for that purpose, a much more precise IW is going to be revolutionary in suppressive capabilities. You teached us a thing or two about suppression modelling a while ago ;)

A helmet mounted display would offer certain advantages (firing around corners without sticking your head around corners) but displays aren't very heavy* and you'll still want direct optics on the gun, if only for the power-less backup option.

The "normal" firing position associated with rifles is only partly to look down the sights though, it also offers stability. I'm not sure how far you'd be able to hold a worthwhile group without a decent braced position.

That said, the US army looks like they're going to have helmet mounted displays anyway** which claim to be good to 300m with an M4, though they don't give details on the targets in question.

* https://static1.squarespace.com/static/57dc111b414fb5bdb26a7ff6/t/593ff72a9f7456b671728248/1497364272271/TAC-EYE+2.0.pdf

** https://www.forbes.com/sites/davidhambling/2020/11/27/us-soldiers-hail-armys-futuristic-goggles-something-almost-out-of-a-video-game/

 Is there any information available yet as to the actual armor penetration of the 6.8 NGSW round in tungsten or steel penetrator form?  If not, based on the current state of the art, what is it likely to be?  I know this has been discussed, but I can't recall the answers.

Is the Anthena PPI-style AP bullet considered the most effective, or has that been improved upon?

stancrist said:

Actually, the .276 Pedersen was a 7mm cartridge, not 6.8mm.

Yep, but I was referring more to the round muzzle energy (~2800 J) and impulse (6.9 N.s) than to the bullet diameter.

stancrist said:

I don't follow.  How does it explain why SOCOM resumed work on the 6.5 CM program?

The training / practice 6.8x51 mm does not seem to deliver something the 6.5 mm Creedmoor is not already doing, the GP & SP loads are still in the development phase and there is no "match" ammo planned.

Special Forces shoot  a lot of ammo and they need to replace their weapons every ~5 years, so they could adopt 6.5 mm weapons now and wait until 2027-2028 in order to switch to the 6.8 mm if the cartridge is still there.