Militarys new ammo

[David Milisock]

Sigs new military round looks badass. 6.8x51. Necked down 308 to .277. Had to put a steel sleeve around the head for the 80000 psi it generates. 135 gr at over 3000 fps. Basic short .270 . They finally figured out that the 556 is a pc of crap. Only took 54000 dead GI's in Nam to get it right. "we the people" Rob

Luckily for me I was young enough for the issues to have been resolved with the M16 before I got into the fray. The 5.56 has in my opinion within current technology reached the end of it ability to be improved.

I've carried under field conditions the M2 Carbine in M1A1 configuration, the M14, 16A1, 16A2 CAR15 and several bolt rifles in different chamberings.

I'm pessimistic about the new cartridge and the rifle under general combat conditions. As a special designated rifleman concept it has its appeal.

 

[Rsadams]

Putting our eggs in the digital basket , gps etc... All taken out with one simple EMP burst... Unfortunately they are also betting that our engagement will be long distance like afghan land not Vietnam territory again... Never know what the future holds and that's why you can't prepare for everything.... When I moved to Bastrop TX I came from Corpus Christi and had everything you would need to get by in a hurricane situation.... Unfortunately not any of it was fire proof and burned up in the 2011 Bastrop complex fire.... Once again you can't be ready for everything...

 

[Brians356]

I am more concerned with conflict that is going to happen here !

Why? One side is armed to the teeth.
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[Brians356]

The slope of the pressure curve is exponential,

Incorrect.
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[jdh47]

Complicated case. Overpressure load. What could go wrong? Of course, our rich uncle can afford it.

 

[Brians356]

Complicated case. Overpressure load. What could go wrong? Of course, our rich uncle can afford it.

"Overpressure" according to which standard?
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[dantiff2]

Very interesting for those who like to get more technical:

 

[DaveTooley]

I'll throw this out.
How many gunsmiths will chamber currently available actions for an 80K PSI round?
That's assuming it's reloadable which would be a requirement for commercial success.
I'm not sure I will.
Pretty sure it will violate rule #1.

 

[dantiff2]

The factory Sig "Cross" is already chambered in the 277 Sig Fury (6.8x51). What makes it any better than say a custom action? Is it built better/different to handle the 80,000K? They sell the same gun in 6.5 Creed and 308 Win.
Dan

 

[dantiff2]

You can even buy brass for this round but it is "normal" brass and not the two-piece steel head stuff. Wonder how many guys will try to get 80K out of this brass? : O

277 Fury SIG Primed Brass - 100ct

277 Fury SIG Primed Brass - 100ct

americanreloading.com

 

[Adam in WI]

Wonder how many people are loading close to 80k psi anyway and not realizing it

 

[M-61]

Sigs new military round looks badass. 6.8x51. Necked down 308 to .277. Had to put a steel sleeve around the head for the 80000 psi it generates. 135 gr at over 3000 fps. Basic short .270 . They finally figured out that the 556 is a pc of crap. Only took 54000 dead GI's in Nam to get it right. "we the people" Rob

It’s 58,000+
And still counting

 

[Walt Krafft]

I'll throw this out.
How many gunsmiths will chamber currently available actions for an 80K PSI round?
That's assuming it's reloadable which would be a requirement for commercial success.
I'm not sure I will.
Pretty sure it will violate rule #1.

I am with Dave on this. I have played with the cartridge and know for a fact you need pressure measuring equipment to know what pressure you are loading to. If you load using the pressure signs we are used to, you will go way past 80k. The cartridge case is no longer the weak link, what is? And don't assume the case is reloadable, sizing the head is a b-----.

 

[dantiff2]

I am with Dave on this. I have played with the cartridge and know for a fact you need pressure measuring equipment to know what pressure you are loading to. If you load using the pressure signs we are used to, you will go way past 80k. The cartridge case is no longer the weak link, what is? And don't assume the case is reloadable, sizing the head is a b-----.

Do you have any real world numbers loading this cartridge with standard brass at max operating pressures?

 

[Walt Krafft]

Do you have any real world numbers loading this cartridge with standard brass at max operating pressures?

I do not. It is pretty much between a 260 and a 7-08.

 

[dantiff2]

Wonder how many people are loading close to 80k psi anyway and not realizing it

After seeing this, I doubt too many will ever make it to 80K before losing the case head or having a vaporized primer pocket.

 

[Timberyote]

In 1945 the British Army developed the 280 British. https://en.wikipedia.org/wiki/.280_British

In 1948 they developed the EM1. https://www.forgottenweapons.com/rifles/em1/
which was later that year became the EM2. https://en.wikipedia.org/wiki/EM-2_rifle

It was destined to be the NATO cartridge, but the US were determined to have their cartridge (7.62x51), which was developed by Winchester in 1952 as the .308 Win https://en.wikipedia.org/wiki/.308_Winchester and adopted as the NATO cartridge 7.62x51 in 1954. https://en.wikipedia.org/wiki/.308_Winchester and https://en.wikipedia.org/wiki/7.62×51mm_NATO

It seems that we are coming full circle to what should have been.

 

[dantiff2]

I was at the local range one day and there was a feller down a few benches, shooting an AR. Just blasting away and having a good time. He cleaned up his stuff and went on his way. After my sons and I were done, we went over and notices a pile of brass the man had left behind. All 308 Win, factory Hornady stuff. I say factory because the primer pockets were still crimped so I'm 99% certain they were not reloaded but let me tell you! I've never seen such over-pressure signs in my life! Brass flow into the ejector more than i've ever seen and brass smears on the case head. A few even had pin holes in the edges of the primers with a small amount of black gas that escaped. These brass were TRASHED! I only wonder how HOT these were and how long that poor gun would last by shooting them..
Dan

 

[Adam in WI]

Who knows who built that gun though. Low quality bolt with a large firing pin hole? Over gassed? Lots of unknown information to just assume it's over pressure.

 

[dantiff2]

Who knows who built that gun though. Low quality bolt with a large firing pin hole? Over gassed? Lots of unknown information to just assume it's over pressure.

Agreed. Not going to argue that point but the gun was spitting out brass at about 2-3 oclock consistent pattern and the rims were not ripped off, nor did they show any signs of a timing issue or over gas like you'd expect. Just blown out primers ( on the sides not center around the firing pin) and ejector flow so bad that I'm surprised that there were no failure to eject, that I saw. The ejector flow was 60 thou or more : O. I've tempted fate before and pushed some reloads into pressure (doing my own testing) and this was WAY beyond that. The bunter stamping was even ruined on some. For a factory round to exibit those signs, I'm not sure a bolt could be the blame.
Dan