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Discussion Starter #1
Good morning.
I’ve been reading about the new 277 Sig Fury that was designed for the military. It’s basically just a 270-08 that can safely operate at 80k psi.
This got me thinking. What if you were to do the same thing to the 6.8 SPC? What would the performance increase be with a 110-120 grain projectile from a 16” barrel at 80k PSI? This forum has some of the brightest minds I’ve seen when it comes to rifle performance so what say you?
 

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Considering the 277 Fury has yet to come to fruition, I wouldn’t hold my breath on someone trying to make a 6.8 Fury. The sig Cross was never commercially released in the Fury caliber, and Sig doesn’t even list 277 Fury ammo on its own website.

A standard 6.8 bolt likely wouldn’t last long at 80k PSI. That pretty much leaves two options for a 6.8 Fury. Either a bolt action, or something like the old Remington R-15 in .30 RAR, which used a modified upper, bolt, carrier, and barrel extension which allowed the use of an LR-308 bolt to be used in an AR-15 receiver.
The R-15 And The .30 RAR
 

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For every 5000 psi in the 55-60K range you gain apx 100fps. I'm not sure the gain would carry at the same rate when pushed to 80k.
I've run the 6.8 up to 65 and gained 200fps over factory velocities without any problems. Above that the bolts or brass cannot handle the pressure. Stick one in a short action bolt gun with the 2 piece cartridge and I'm sure it could be pushed to 80.
 
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Ohhhh that’s what’s taking so long? I could have sworn I read somewhere it was already approved. Maybe it was just that they had submitted it. Either way, I hope it works out. This could be a step in a great new direction that will lead to all kinds of new advancements.
 

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Discussion Starter #6
120 grain SST 3000 FPS with and 16” ARP barrel. That would be a pretty sweet setup.
 

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AR barrels have a pretty generous chamfer to help feed the auto loader. Bolt guns do not so the cartridge is supported better, the case will not rupture as early. I'm sure you can push a 6.8 bolt gun much faster than a 6.8 AR.
 

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As someone who has spoken with Sig at length about this cartridge and the CROSS rifle I can say it's a unicorn. It does exist but as of right now the cartridge is all being used for the Next Generation Weapons testing for the US Army. They did not (like all other manufacturers) plan on fabrication facilities being shut down and they didn't plan for a massive run on ammunition and firearms like we have right now. I expect Sig will have some of the ammunition available after the first of the year and then they will be able to sell the CROSS in .277 Sig Fury. When that happens I'll have mine as I am in the queue for one of the first couple of hundred of the weapons and a few hundred rounds of the ammo.
 

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Wondering if it would be a good candidate for an AR 10. Definitely wont work in a 15.
 

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Wondering if it would be a good candidate for an AR 10. Definitely wont work in a 15.
You might be surprised on the AR-15 chamber. I would not want a cheap AR Upper to test it. I've looked into a machined cold rolled forged billet monolithic receiver just to see and it honestly wouldn't be that expensive relatively speaking. It'd be somewhere in the $2500-$4000 range but your barrel would have to come from Sig Sauer at first unless someone else is making them for Sig and they are able to sell them without licensing problems and royalties.
 

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Wondering if it would be a good candidate for an AR 10. Definitely wont work in a 15.
85k is a lot of pressure for an AR10 especially since the barrels have a big chamfer at the breech to aide in feeding.
 

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This 6.8 Western sounds interesting 175gr bullet traveling at 2840fps at 65K psi.

Thats a 40gr heavier bullet just 160fps off the Fury, but still at normal pressures. Of course there is an 8" difference in barrel length.
 

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Discussion Starter #16
I wonder if Sig did do to the 6.8 what it did to the 277 Fury if it would make a more suitable military round. Less weight, smaller size and more capacity magazines. A 110 grain projectile at around 3100fps would still be traveling over 2200fps at 350 yards.
 

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I wonder if Sig did do to the 6.8 what it did to the 277 Fury if it would make a more suitable military round. Less weight, smaller size and more capacity magazines. A 110 grain projectile at around 3100fps would still be traveling over 2200fps at 350 yards.
I think they designed the fury based on the Army's requirements. All the rounds in the contest have similar properties. This was a little different challenge than in the past as it was weapon and round as one design.
 

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Discussion Starter #19
 
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