Will Australia adopt the 6.8x51mm ?

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Will Australia adopt the 6.8x51mm ?

Post by Border_Bloke » 18 Jun 2022, 6:40 pm

I'm sure most would be aware that the US has just adopted the SIG Sauer MCX Spear in the 6.8x51mm "Sig Fury" cartridge (the one with a stainless steel base and brass case that runs at 80,000 psi pressure).

Looks like Australia will be looking for a new "close combat assault rifle" in 2024/25 and apparently Aquaterro is offering them the MCX spear (https://www.thefirearmblog.com/blog/2021/06/11/sig-ngsw-for-australia/).

Nioa was announced as the prime contractor for first part of the system "tranche-1 sniper system and close combat system" last year https://www.nioaland159.com.au/. There is a bit more on the ADF web site https://www.defence.gov.au/project/lethality-system-tranche-1-sniper-system-and-close-combat-system.

The US adopted the 6.8x51 / SIG Fury to overcome body armor in "peer level adversaries" (ie Russia and China). The hunting load sits somewhere between the 270 Winchester and 270 WSM in velocity (but from a 16" barrel). It would be interesting if ADI start making the ammo here, although the only civilian rifle so far is the SIG Cross (and we can't have that in NSW because of the folding stock).
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Re: Will Australia adopt the 6.8x51mm ?

Post by bigpete » 18 Jun 2022, 7:54 pm

Wouldn't that pretty much be a 260 Remington?
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Re: Will Australia adopt the 6.8x51mm ?

Post by Border_Bloke » 18 Jun 2022, 8:45 pm

260 rem is 6.5mm (.264").
The new "6.8" is .277" (same as the 270 Win) - so I guess it's closest to the 270-08 (although it's running at 80,000 psi chamber pressure).

It supposedly produces 3000 ft/s with a 135gn bullet, and 2,950 ft/s with a 140gn bullet (and that's out of a 16" barrel).That's what a 270 Winchester will do from a 24" barrel, and about 200 ft/s faster than the 260 rem does from a 24" barrel.

There are some comparison photos with it and the 308 & 6.5 CM here https://www.gunsamerica.com/digest/277-sig-fury-demystified/.
Ian McCollum did a video on the MCX rifle a couple of weeks ago https://youtu.be/MTZRCEh1Czg.

He mentions that all of the reviewers so far have used the brass-cased low power training ammunition (135gn bullet at 2,750 ft/s).
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Re: Will Australia adopt the 6.8x51mm ?

Post by Larry » 19 Jun 2022, 10:35 am

My 308 runs a 155grn at 3020fps so that should do the same job given it is speed that defeats amour.
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Re: Will Australia adopt the 6.8x51mm ?

Post by bigrich » 19 Jun 2022, 3:01 pm

so america's forgotten why nato was formed :P during WW2 supplies of ammo to the allies was a logistical nightmare . korean war was the same thing . different nations using different ammo . hence the adoption of the 7.62x51, used in civillian sporting rifles as the 308 win. millitary preasures are higher , but it's the same round essentially . same deal for 223 . all allies in battle could source ammo of each other during a conflict . supply problem solved

now america's gone and adopted a new round ,nato allies will have to follow suit . but i agree with why they did it . being able to peirce a opposing forces body armour is a advantage .

i actually considered a 270-308 wildcat for a rifle build a while ago . maybe the US millitary posts on enough gun too :lol:

as a oddball fact , WW2 british tanks machine guns were chambered in 7.92 BESA . which enabled them to use captured german 8x57 ammo :wtf:
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Re: Will Australia adopt the 6.8x51mm ?

Post by mickb » 19 Jun 2022, 11:12 pm

If we are told to we will :)
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Re: Will Australia adopt the 6.8x51mm ?

Post by wanneroo » 20 Jun 2022, 10:07 am

I wouldn't worry too much for now, the US military is going to continue to use 5.56 for decades to come. The 6.8x51 is going to be issued to the combat arms and anyone else that needs a rifle will get an M4 in 5.56. No reason for Australia to suddenly change.
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Re: Will Australia adopt the 6.8x51mm ?

Post by Border_Bloke » 23 Jun 2022, 8:41 am

Larry wrote:My 308 runs a 155grn at 3020fps so that should do the same job given it is speed that defeats amour.


Out of a 308 Winchester? Or are you talking about some other 308 caliber cartridge? If it's a 308 Win, what is the barrel length?

I'm curious because 3020fps is what you would expect from a 24" barrel 30-06 using 150gn bullets, I would have though you'd need a 30" barrel to get that sort of velocity from a 308 Winchester.

The interesting thing with the 277 Fury / 6.8x51 cartridge is that the velocities are from a 16" barrel. You would expect to get around 3150fps to 3200fps from a 22" barrel. That's about 270 WSM 24" barrel velocities (although granted, it's probably loaded with fast ball powder to make it more efficient in a 16" barrel, which is what Winchester did with the early 308 loads).
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Re: Will Australia adopt the 6.8x51mm ?

Post by geoff » 23 Jun 2022, 11:21 am

Can't wait to see the umpteen forum posts about "why won't anyone rebarrel my 308 to this new calibre? 80k psi is fine on an old SAAMI action"
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Re: Will Australia adopt the 6.8x51mm ?

Post by Larry » 23 Jun 2022, 4:23 pm

First comment would have to be why would you make such a caliber? with 6.5 and 7mm already available a 6.8 *51 is just 0.2mm different from a 7-08 I dont see there being much difference. Yes I see they are going to push it to higher pressures but that could be done with the current 7-08.

As for my 308 I can get those velocities from a 28 inch barrel and my 30 inch quite easily the 28 inch is on a rem 700 action and no blow ups yet the other rifle has a custom action that is very robust.
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Re: Will Australia adopt the 6.8x51mm ?

Post by Border_Bloke » 23 Jun 2022, 7:06 pm

Ahh, 28” barrel that explains it!

It’s not a new caliber- it uses .277” diameter bullets the same as the 270 Winchester, 270 WSM and 270 Weatherby magnum.

Edit: I just found out that the US government called for the same specs as the 270 WSM but from a 16” barrel.
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Re: Will Australia adopt the 6.8x51mm ?

Post by JohnV » 23 Jun 2022, 7:42 pm

They might adopt the higher pressure version as a sniper round .
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Re: Will Australia adopt the 6.8x51mm ?

Post by mickb » 26 Jun 2022, 6:08 pm

Larry wrote:First comment would have to be why would you make such a caliber? with 6.5 and 7mm already available a 6.8 *51 is just 0.2mm different from a 7-08 I dont see there being much difference. Yes I see they are going to push it to higher pressures but that could be done with the current 7-08.

As for my 308 I can get those velocities from a 28 inch barrel and my 30 inch quite easily the 28 inch is on a rem 700 action and no blow ups yet the other rifle has a custom action that is very robust.


Because army leaders, retired generals sitting on advisory boards in the private sector and CEO's for prime vendors all went to school together, and if defence doesnt keep overhauling its stuff a lot of them are out of a job. :
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Last edited by mickb on 26 Jun 2022, 6:16 pm, edited 1 time in total.
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Re: Will Australia adopt the 6.8x51mm ?

Post by northdude » 26 Jun 2022, 6:13 pm

If its all about defeating body armor Why not just keep existing cal and teach your men to head shoot...
22 hornets and most things 6.5
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Re: Will Australia adopt the 6.8x51mm ?

Post by SCJ429 » 26 Jun 2022, 7:52 pm

Larry wrote:First comment would have to be why would you make such a caliber? with 6.5 and 7mm already available a 6.8 *51 is just 0.2mm different from a 7-08 I dont see there being much difference. Yes I see they are going to push it to higher pressures but that could be done with the current 7-08.

As for my 308 I can get those velocities from a 28 inch barrel and my 30 inch quite easily the 28 inch is on a rem 700 action and no blow ups yet the other rifle has a custom action that is very robust.

My 308 can shoot a 220 grain bullet faster than 3,200 feet per second using a 30 inch barrel but it burns nearly 120 grains of powder to do it. Roy Weatherby finest case.
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Re: Will Australia adopt the 6.8x51mm ?

Post by Billo » 26 Jun 2022, 9:21 pm

I would say no
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