nincomp said:

I wonder if they used the 277 Fury case shape

I'd be astounded if they weren't copying the same case dimensions given their goal to have some commonality with the US 6.8. 

The SIG Spear seems to have the ability to fire both standard ~60kpsi brass ammo as well as ~80kpsi hybrid ammo, at least from the few youtube clips we've seen.

I imagine the Australians are interested in a similar goal? This domestic case that they can make royalty free, that offers 'general purpose' performance, but retain the ability to fire high pressure US AP when the AUKUS balloon goes up?

All speculation on my part here, I just have that little insta post to go on. 

gatnerd said:

       nincomp said: I wonder if they used the 277 Fury case shape

I'd be astounded if they weren't copying the same case dimensions...

Ditto.

gatnerd said:

This domestic case that they can make royalty free, that offers 'general purpose' performance, but retain the ability to fire high pressure US AP when the AUKUS balloon goes up

Quite logical.

EmericD said:

Is it a crack running around the "6.8x51" mark, and an ejector mark between the "BB" and the kangaroo?

Concur on the mark between the "BB" and the kangaroo being an indentation from the ejector.

I think it is not a crack at the "6.8x51" mark, but perhaps an impression of the extractor groove on the bolt face.

stancrist said:

I think it is not a crack at the "6.8x51" mark, but perhaps an impression of the extractor groove on the bolt face.

Could be. My experience is that the extractor mark is generally found inside the groove, where the extractor try to shear the rim.

Looks like that this case is operating just below the threshold of catastrophic failure.

EmericD said:

My experience is that the extractor mark is generally found inside the groove, where the extractor try to shear the rim.

Not the groove in front of the cartridge case rim.  The groove / channel machined into the bolt, into which the extractor is fitted.

Although to make that shape of impression on the case head, the extractor channel bottom would have to be rounded instead of flat.

Sweden reportedly adopting a new 7.62x51 infantry rifle, with an eye to possible future conversion to 6.8x51.

https://www.ar15.com/forums/General/Sweden-goes-ahead-with-new-service-rifle/5-2633465/#i103427018

https://forums.delphiforums.com/autogun/messages?msg=7952.27

So the list of potential NGSW users is now up to three (US, Australia, Sweden).  Who will be next?  

Didn't Sweden just go with 7.62 NATO?

graylion said:

Didn't Sweden just go with 7.62 NATO?

Uh, yes.  

stancrist said:

Sweden reportedly adopting a new 7.62x51 infantry rifle...

At this year's SHOT show, Geissele stated that they are using a proprietary upper, forged bolt, barrel extension, barrel nut, gas system and magazine on their new 6mm ARC.  They said the bolt is forged from a new "Carpenter 158+ alloy".    That alloy does not yet show up on Carpenter Steel's website, so I don't know any more about it.  

 They have also modified the upper, moved the foreward assist, riveted a steel insert in the cam-pin race to prevent steel to aluminum contact from bolt movement, and goodness knows what else.

They have modified the rifle so much that many parts are not compatible with other AR15's.  They did not mention widening the magazine well, but it is not out of the question.  Their estimated sales price is $3,500 to $3,800, so about 50% more than their own boutique "Super Duty" 5.56 rifles.

nincomp said:

At this year's SHOT show, Geissele stated that they are using a proprietary upper, forged bolt, barrel extension, barrel nut, gas system and magazine on their new 6mm ARC.

They have modified the rifle so much that many parts are not compatible with other AR15's.  They did not mention widening the magazine well, but it is not out of the question.

According to this report, Geissele's "new" 6mm ARC magazine is identical to ASC mags, differing only in a very minor alteration of the follower.

YouTube

6mm ARC vs 6.5 Grendel magazines. Geissele, ASC, Duramag, AR Stoner, Elander {UPDATE}