Lions and Tigers and Bears, Oh My!

80,000PSI, 3 piece cases and a special factory action to handle the pressure.

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.277 SIG Fury Demystified


Why .277 or 6.8?
As many of you know, traditionally the best bullets are not found in .277 caliber. While a few good ones exist, most of the favorite bullets on the market are .260 caliber (6.5), .284 caliber (7mm) or .308 caliber. So why did SIG choose .277 (6.8mm)?

The answer is they didn’t. The U.S. military wants a new belt-fed machine gun and put out a contract for one. SIG entered a belt-fed machine gun hoping to win the contract. The military specified the caliber of 6.8 or .277. Of course, the military wants the cartridge lighter and more powerful so SIG began developing the .277 Fury for that contract. SIG has been selected as one of the three finalists for the contract and will be going into full production with the .277 SIG Fury for the military. The commercial market gets to reap the benefits of over two years of R&D with the cartridge for the military.

The other two finalists for the belt-fed contract are General Dynamics and Textron.

To summarize the .277 SIG Fury was designed for the military. Specifically for SIG’s belt-fed machine gun entry.

80,000 PSI
A standard cartridge, like a .308, is producing (on the high side) around 60,000 PSI. A magnum cartridge, like .300 Remington Ultra Magnum, can produce as much as 66,000 PSI.

SIG’s Fury is working at more than 80,000 PSI. They have created and tested proprietary blends of faster burning powder that help safely push those pressures and velocities while maintaining good accuracy.

80,000 PSI
A standard cartridge, like a .308, is producing (on the high side) around 60,000 PSI. A magnum cartridge, like .300 Remington Ultra Magnum, can produce as much as 66,000 PSI.

SIG’s Fury is working at more than 80,000 PSI. They have created and tested proprietary blends of faster burning powder that help safely push those pressures and velocities while maintaining good accuracy.

80,000 PSI is the key to getting high speeds from a short barrel. It’s not using standard powders, either. These are new proprietary powder blends SIG has developed while developing this ammo for the military.



Sweet, I’ll Have Ol’ Reliable Rechambered in .277 Fury…
Can you have your gunsmith rechamber your favorite rifle in SIG Fury? Technically, yes. SIG has even tested several actions from other manufacturers. A Remington 700 can certainly handle it, but SIG doesn’t recommend it, and for good reason.

That much pressure can be handled by existing actions, but they are not designed for it and it’s going to wear on them. “We Built the Cross rifle like a tank,” SIG says. Everything about this new action is engineered for longevity under the high pressure produced by this cartridge.

.277 Only?
SIG will have the .277 ammo available commercially in 2020. This is SIG’s first proprietary rifle cartridge. But they already have other calibers in the works. They confirmed that a 6.5mm case is on the way and that we may see long action calibers follow.
 
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This will probably NOT be appreciated . . . but WHY would you even want to . . :( ?!



 
Any MV written up?

In the link they are talking "140-grain bullet will attain a velocity of more than 3,000 FPS from a 16″ barrel. Exact chronographed velocity won’t be finalized until it’s checked in SIG Cross production rifles but at least 3,000 FPS is certain."

But all seems to be knowledgeable? guessing.

This added pressure will drive a 135-grain bullet from SIG’s Hybrid Match cartridge 3,000 fps from a 16-inch barrel, and produce 2,694 ft.-lbs. of energy. The 135-grain bullet has a respectable .488 G1 BC.

SIG’s 277 Fury Hybrid Hunting load features a 140-grain bullet with a .508 G1 BC, launching from a 16-inch barrel at 2,950 fps. That one produces 2,706 ft.-lbs. of muzzle energy, too.

277 SIG Fury: SIG Sauer Unveils New Caliber With Hybrid Case Design

Maybe SIG don't know just yet or it ain't reaching what they think it should.
 

ugly

LE
Moderator
Any MV written up?
I missed the link
“ 140 Grains, 3,000 FPS, 16″ Barrel

There have been all kinds of numbers circulating, but the facts are that a 140-grain bullet will attain a velocity of more than 3,000 FPS from a 16″ barrel. Exact chronographed velocity won’t be finalized until it’s checked in SIG Cross production rifles but at least 3,000 FPS is certain. Obviously, longer barrels are going to mean even faster speeds.”

Disappointed with those speeds to be honest, high pressure composite cartridge with excellent bullet choices and 3000 FPS seems a bit pedestrian especially when I can get that from a tight chambered 7.62 in a 55 mm case using 48 grains of IMR 4895 which in a nice loose military chamber is normally 2700 FPS!
Still it’s a starting point I suppose and could prove to be a great way of development in composite cases! I wonder if they will release for reloaders or will we be forced to use brass with a lower pressure curve?
 

ugly

LE
Moderator
In the link they are talking "140-grain bullet will attain a velocity of more than 3,000 FPS from a 16″ barrel. Exact chronographed velocity won’t be finalized until it’s checked in SIG Cross production rifles but at least 3,000 FPS is certain."

But all seems to be knowledgeable? guessing.



277 SIG Fury: SIG Sauer Unveils New Caliber With Hybrid Case Design

Maybe SIG don't know just yet or it ain't reaching what they think it should.
Typing together I think but I agree a high pressure cartridge should do better given time
 

ugly

LE
Moderator
That would be wicked on the rabbits. What about barrel life? 10 seconds?
I’ve been pushing 40 grain vlds moly coated at 4400 FPS from my .22-250, no sign of wear yet, mind you it’s a Sako 85 stainless
 
I’ve been pushing 40 grain vlds moly coated at 4400 FPS from my .22-250, no sign of wear yet, mind you it’s a Sako 85 stainless
Goodness. That is zipping along! I have not chronographed my home rolled (under grown up supervision) 308s yet.
 

ugly

LE
Moderator
Goodness. That is zipping along! I have not chronographed my home rolled (under grown up supervision) 308s yet.
It’s fine I checked the pressure readings and also the rifle whilst not new had only fired 5 rounds before I got it as I had loaded for the owner and went with him to buy it!
The Sako 85 is a really strong action
Eta it does for anything in a straight line out to about 500 yards, properly fecks over magpies
 
I’ve been pushing 40 grain vlds moly coated at 4400 FPS from my .22-250, no sign of wear yet, mind you it’s a Sako 85 stainless

Would that be a 1:14 twist rate?
Have you by chance tried anything a bit heavier, 60gr/62gr?
 

ugly

LE
Moderator
Not checked the twist rate it’s happy with most bullets essentially I roll the lighter ones when available as it’s more than enough for pests and I have a lot of 50 & 55 grain factory loads to get through
 
Not checked the twist rate it’s happy with most bullets essentially I roll the lighter ones when available as it’s more than enough for pests and I have a lot of 50 & 55 grain factory loads to get through

No props mate, am just on the very outer reaches of an interweb correspondent about
60 grains or heavier for a Winchester 220 swift, 1:14 twist rate.
I just thought your practical experience may have made me look good. :cool:

In the end he's found that a 60g Hornady FBHP, 41.0g H4350 at 3,628 fps, all go into .6” for three.
He does have a .22-250 which gives him 3,744 fps with the same bullet and powder load, 1:14 twist.

Maybe something to dabble with, carefully.
 

ugly

LE
Moderator
No props mate, am just on the very outer reaches of an interweb correspondent about
60 grains or heavier for a Winchester 220 swift, 1:14 twist rate.
I just thought your practical experience may have made me look good. :cool:

In the end he's found that a 60g Hornady FBHP, 41.0g H4350 at 3,628 fps, all go into .6” for three.
He does have a .22-250 which gives him 3,744 fps with the same bullet and powder load, 1:14 twist.

Maybe something to dabble with, carefully.
No two barrels give exactly the same performance but experimentation is the only way to go! Usually a faster twist stabilises heavier bullets but it all depends on how fast you are pushing it and hearsay and internet waffle can’t replace experience gained from doing it yourself.
Every load I develop must group first and foremost then it’s velocity
 

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