The Down Range Forum

Member Section => Building America's Rifle => Topic started by: Rastus on October 22, 2023, 01:40:26 PM

Title: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: Rastus on October 22, 2023, 01:40:26 PM
Have I been asleep or what?  This 6.8 x 51 mm is one hot round with 80,000 psi chamber pressure.  Designed to defeat body armor on the battlefield.  Stainless steel base coupled to brass bullet via aluminum lock washer...huh??....because plain brass can't take it!  That's going to be some expensive ammo and I wonder if it can be reloaded.

140 grain bullet at 3,000 FPS out of a 16" barrel....whoa, now that's a horse.  This is in the Sig MCX Spear platform which I have not yet fired but I have drooled over. 

Maybe retooling for this is why Lake City isn't selling any civilian overruns now.  Who knows?

Does anyone here have any idea when the MCX Spear in 6.8 x 51 mm will be available to civilians? 
Title: Re: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: kmitch200 on October 23, 2023, 02:09:59 PM
Probably not in our lifetime.
Lake City canceled civilian sales contracts, I don’t think this was by accident.

The last rumor I read, the hot ammo was supposed to be for issue to use in combat. A lower pressure round was the practice stuff.

My pure wild ass guess is the hot ammo is going to beat that Sig carbine to pieces. Just what you want on a 2 way shooting range!  ::)
Title: Re: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: Rastus on October 23, 2023, 11:00:47 PM
The full strength ammo isn't available to civilians.  Nor, I think, the Sig chambered for it. 

I hope the Sig doesn't fall apart on our troops. 

But...one day it will be available to civilians...and I want one!!!
Title: Re: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: alfsauve on October 24, 2023, 10:57:22 AM
The full strength ammo isn't available to civilians.

So can I get reloading dies for it?   
Title: Re: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: Rastus on October 24, 2023, 01:41:43 PM
Yes but for the .277 Fury but maybe not the.277 Sig Fury.  https://www.natchezss.com/forster-bench-rest-full-length-die-set-277-fury (https://www.natchezss.com/forster-bench-rest-full-length-die-set-277-fury)

The Sig Fury is the 80,000 psi and the 277 Fury is the normal 65,000 psi max pressure.

The Sig Fury cartridges may be made of unobtanium right now.

Picture in the article below:
https://www.outdoorlife.com/story/guns/rise-of-the-270s-rifle-ammo/ (https://www.outdoorlife.com/story/guns/rise-of-the-270s-rifle-ammo/)
Title: Re: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: Big Frank on October 27, 2023, 12:59:26 AM
While you're waiting, you can buy a 7.62x51 mm pistol version with a 13" barrel that only weighs 0.1 pounds more than an M16A2 or M16A4 with a 20" barrel. I wonder which one would be more effective at any range beyond a stone's throw?
Title: Re: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: Big Frank on October 27, 2023, 01:28:40 AM
Am I the only one who thinks the .276 Pedersen or .276 Enfield should have been adopted a century ago? Or the .280 British at the end of WWII? I think it would have saved us a lot of trouble, switching from .30-06 to 7.62x51mm, to 5.56x45mm, almost to 6.8 Remington SPC (.277x43mm), to .277 Fury or 6.8×51mm Common Cartridge.

The .276 Enfield (7×60mm), designed in 1912, with a 165 gr. bullet at 2,785 ft/s developed 2,842 ft⋅lbs of energy at the muzzle. That's more powerful than the 7.62x51mm with a 147 gr. bullet at 2,800 ft/s developing 2,559 ft⋅lbs at the muzzle. A heavier bullet with better sectional density, at nearly identical speed and a good 11% more power, all 42 years before the 7.62x51mm was invented. They could have improved the cartridge without changing bullet diameter again and again, and still been using it today.
Title: Re: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: Rastus on July 29, 2024, 07:02:12 PM
Well, I know someone who ordered one of these on day one so he has another 3-5 week wait.  The full power bimetal round is $2,800 for 920 rounds...so a little over $3 a round.

I'll let you guys know how it runs when he gets it...and hopefully I get to put a few rounds downrange as well....
Title: Re: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: Big Frank on July 29, 2024, 07:18:49 PM
What's the operating pressure of that round again? On par with the center of a neutron star? ;)

P.S. Never mind. I see it there in the first post, 80,000 psi chamber pressure. That seems like it would eat guns for breakfast and chew on the pieces all day.
Title: Re: US Army XM7 in 6.8 x 51mm (.277 Sig Fury NOT a .277 Fury) The New AR
Post by: Rastus on July 29, 2024, 07:23:08 PM
Yeah.  Probably will need a new barrel at 3,000 rounds or less.