6.8 if...... it ends up in widespread U.S. service would be a third rifle cartridge after 7.62 and 5.56 for NATO members. 

At this time NATO members can use 5.56 or 7.62. They are not forced to choose. Even if 6.8 is adopted by the U.S. , the U.S. will still continue to have weapons in 5.56 and 7.62.

You seem to be missing the point.  Both 7.62 and 5.56 were "forced" (by the US) upon NATO.

NATO adopted 7.62 (over .280) due to US insistence upon a full-power, .30 caliber cartridge.

When 5.56 became the US standard rifle caliber, it in effect became a de facto NATO caliber.

The same thing will almost certainly happen if the 6.8 is fielded by the US Army as planned.

I'll agree that 7.62 was forced on NATO by the U.S.

5.56 was an option when adopted as a second standard caliber. Many NATO allies stayed with 7.62 for years after 5.56 was an option. 

Same will be true IF... the U.S. actually adopts 6.8. The U.S. itself will keep a number of weapons in 5.56 and 7.62.   

If other NATO allies see 6.8 as filling a niche they will use it. If not they will continue on with 5.56.and 7.62.

NATO standardized on 5.7x28mm   as its PDW. The U.S. does not have a large number of weapons in this caliber, it doesn't see the need.  Other NATO countries could have stayed exclusively with 7.62 if they chose to do so. Many of them saw advantages to 5.56 so use it in some weapons as well as using 7.62 in other weapons. If they see a use for 6.8 they may chamber some weapons in that caliber also.

stancrist said:

When 5.56 became the US standard rifle caliber, it in effect became a de facto NATO caliber.

Not really. The US "5.56 mm" was the M193, and what became the second NATO calibre was the SS-109 familly, not really the same cartridge.

By the way, I shot last week a very sweet 5.56 x 40 mm round, with a bullet C7 of 0.208 launched at 945 m/s from a "pseudo Mk12" (18'' barrel).

Hitting at long range was so easy (and fast) it was like cheating.

Sounds like the 5.56mm FABRL*, shown below with the M193.

* originally stood for Frankford Arsenal Ballistic Research Laboratory, but that evidently didn't sound sexy enough as it was renamed Future Ammunition for Burst Rifle Launch.

EmericD said:

By the way, I shot last week a very sweet 5.56 x 40 mm round, with a bullet C7 of 0.208 launched at 945 m/s from a "pseudo Mk12" (18'' barrel).

Was this further work with your Neckless round, or just a shortened 5.56x45?

autogun said:

Sounds like the 5.56mm FABRL*, shown below with the M193.

Quite close.

The cartridge started it's life as a regular 5.56x45 mm M855 from IMI, we removed the bullet, saved the powder, shortened the case by cutting most of the neck, put the powder into the case, then finally seated and crimped the new bullet (4.15 g / 64 gr).

MV was ~945 m/s from a 18'' gas-operated gun, and ~970 m/s from a 24" bolt-action rifle*.

Now, we are going to do the same thing but starting with M855A1, just to see if we can drive the same bullet at 3000 fps from a 14.5" barrel, and maintain a supersonic range of 900+m from a carbine.

*: EDIT - fired in regular 5.56x45 mm chamber.

EmericD,

what’s the end game with the work you are doing on 5.56mm rounds ? Does the (French) army intend to procure an improved round to re fit into the HK416f ? 

njb3737 said:

what’s the end game with the work you are doing on 5.56mm rounds ? Does the (French) army intend to procure an improved round to re fit into the HK416f ?

We are trying to explore all the technical possibilities available to enhance the 5.56 mm & 7.62 mm (lighter cases, advanced propellents, better bullets), then we will decide if "the juice worth the squeeze".

Additionally, those results will "feed" a technology program run by the European Defense Agency (including governments and manufacturers), devoted to define and build "a better mousetrap".

From a personal point of view, I would be pleased to see ours 416 FELIN (fitted with those large IR scopes) shooting those enhanced ammo.