The new Sig 277 Fury
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mdThanatos
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Still a lot of information missing on the round itself, and I am not sure it is for sale yet. From one article Sig is saying that while the R700 may be able to support it, the 80k pressure of the round may be damaging to it. This could be a tactic used by them to try and sell more of their rifle, the Cross, or it could be fact. I am not a scientist and have no expertise in the matter to weigh an education opinion on. All I know is, that's a lot of pressure and it is a specialty round so it may not be a worthwhile endeavor.
EDIT
I think you'd probably need a new bolt face/bolt at the very least.
EDIT
I think you'd probably need a new bolt face/bolt at the very least.
Mosin Bubba
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Putting an 80K PSI round in a 60K PSI bolt and chamber probably isn't going to go well.
No it is a different case and wouldn't work.
Varminterror
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No.
mcb
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rambling...
The 700 action (along with most any of the current modern bolt actions) will take the bolt thrust from 80,000 psi in the 277 Fury cartridge no problem. 300 WSM at 65,000 psi produce roughly 11% more bolt thrust on the bolt than 80,000 psi in 277 Fury (same case head diameter at 308 Win). 338 Lapua Mag should produce roughly 16% more bolt thrust at 60,000 psi than 277 Fury's 80,000 psi. The case head failure is usually your failure point, not bolt lugs as you reach or exceed 80,000 psi since that is approaching the yield strength of brass and the brass starts to flow. The 277 Fury address that issue with the hybrid case.
But yes 277 Fury is a completely new cartridge and is in no way compatible with the the 6.8 SPC cartridge.
Going to be a barrel burner no mater what, if they actually run it at those pressures. Stellite barrel liners anyone?
Speedo66
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Here's an article on the ammo and rifle Sig will produce for military and civilian use. MSRP of $1800, they figure a street price of $1600. Nothing there that I can't do without.
They say due to proprietary powder, barrel life will be OK, but OK to whom? It's designed for machine guns where barrels are routinely changed.
https://www.gunsamerica.com/digest/277-sig-fury-demystified/
They say due to proprietary powder, barrel life will be OK, but OK to whom? It's designed for machine guns where barrels are routinely changed.
https://www.gunsamerica.com/digest/277-sig-fury-demystified/
DocRock
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So, I am a curmudgeonly skeptic that looks askance at all "new" cartridges as mostly about newness for the sake of newness. And yet, against my better judgement, I am more than a little interested in the Fury.
I like 18" -20" barrel rifles. But I don't like the velocity penalty associated with long range cartridges in shorter barrels. So, potential 270 Win 24" performance in an an 18" barrel is exciting .
I would love a Mauser 98 action capable of the 277 Fury pressures with an 18" barrel and a traditional steutzen full length walnut stock. Pretty much my ideal rifle.
I like 18" -20" barrel rifles. But I don't like the velocity penalty associated with long range cartridges in shorter barrels. So, potential 270 Win 24" performance in an an 18" barrel is exciting .
I would love a Mauser 98 action capable of the 277 Fury pressures with an 18" barrel and a traditional steutzen full length walnut stock. Pretty much my ideal rifle.
Grab a .224 Valkyrie barrel and enjoy.
Speedo66
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No mention has been made of recoil, will high pressure affect recoil?
mcb
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At first glance I would guess not much different than other cartridge capable of pushing the same bullet to the same velocity. Recoil is governed by the velocity of the total mass (bullet and propellant) ejected out the end of the barrel.
Higher chamber pressures are probably going to result in slightly high muzzle exit pressure which will increase the average velocity of the propellant gases exiting, thus increasing their effect on recoil. But a lower pressure cartridge might actually be more recoil since it will take more slower burning propellant at lower peak pressure to achieve the same muzzle velocity. You would really need to get a 277 Fury and a comparable lower pressure cartridge on a recoil measurement system to say how much but I suspect it will be minor.
Higher muzzle exit pressure will make a breaker more effective, on recoil and your hearing.
Llama Bob
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The unanswered question here is how the keep the brass portion of the case, which is also seeing 80KPSI, from sticking to the chamber wall. There's not much taper there (which is essential to keep bolt thrust down probably). I guess you could beef up primary extraction since the case head is steel. But still, I'm not clear on how this even works.
mcb
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Non-issue, most manufactures proof their rifles daily in production and extraction of proof cartridges is never an issue with properly chamber dimension and finish. A cartridge that has a SAAMI MAP of 65 ksi will usually have a proof pressure range of 87 ksi - 93 ksi (Typically 130% - 140% of SAAMI MAP but there are exceptions) . Nickle plated brass will make stiction less likely and is frequently used on proof loads but not always.
Mosin Bubba
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Thing is, you don't want to keep hammering away on a rifle with proof loads. Those ensure that the rifle will function (or at least not explode) if something Really Bad happens and it's overpressured once, but. 277 Fury shooters could conceivably put a couple thousand rounds down range.
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mcb
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My post was in reference to extraction issues. The extra pressure and brass body of 277 Fury should not cause an extraction issue was my point, using the lack of extraction issues with proof loads was my supporting evidence.
If the rifle is designed to operate at 80 ksi then it would not be hammering away. Run you old Remington model 8 at 60 ksi would tear it apart in relatively short order, that is proof pressures for even the 300 Savage version. An AR-10 operating at 60 ksi will shoot thousands of rounds without issue. I am sure that SIG is designing the firearms chambered in 277 Fury to operate with those pressure and resulting forces. Design geometry and material selection will be driven by those pressures.
Think what its going to take to Proof a 277 Fury. SAAMI (if it was ever to be submitted) would want to see 104 - 112 ksi proof pressure unless SIG could make a case for lower or higher.
Mosin Bubba
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Got it. I was looking more at the thesis of this thread, if you will, asking if a 65K rifle will handle regular 277 loads. You can extract an 90K proof cartridge from a 65K action once, but that doesn't mean it's a good idea to try that repeatedly. You had mentioned how even proof loads need to be slicked up to extract at those elevated pressure levels.
Varminterror
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I don’t think proof load testing practices are representative of the concern @Llama Bob referenced.
Afterall, despite the fact my 6 Creed is specified to 62,000psi, and by your attest, proofed to ~81-87kpsi, I have to hammer my bolt handle open if I run 2 tenths grain over book. Assuredly, I’m not jumping more than 40% pressure with this ~1/2% increase in powder. But I AM crossing a sticky extraction boundary. I can’t imagine how hard stuck a 100kpsi cartridge would be in my rifles.
Just an example.
someguy2800
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Well the case sticking in the chamber is caused by the steel chamber and locking mechanism of the rifle stretching in an elastic mode, while the brass is yielding in an plastic mode. When the pressure subsides the rifle shrinks back elastically to its original size but the brass does not, thus creating an interference fit between the two. The stainless steel case head on the 277 fury should keep the case head from yielding plastically, so all thats needed to keep the brass body from sticking is to make the action strong enough not to stretch too far in length, or the chamber to expand to far in diameter to cause an interference fit.
This is why 40,000 psi in a revolver cylinder can cause the brass to stick in the chamber to the point you have to pound it out, but 80,000 psi in a bolt action rifle doesn't necessarily result in a stuck case.
This is why 40,000 psi in a revolver cylinder can cause the brass to stick in the chamber to the point you have to pound it out, but 80,000 psi in a bolt action rifle doesn't necessarily result in a stuck case.
mcb
Member
someguy2800 beat me to it. It's all about the case head expansion and the Fury hybrid case is suppose to address that. I have proofed a fair number of guns and the only time I have had the body of case stick in a chamber was due to a poorly machined chamber that left features in the chamber walls (ie a chip caught on a reamer leaving a ring etc) that brass flowed into locking the body of the case into the chamber.
mcb
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Two things, as someguy2800 and I mention just prior to this post the hybrid case get rid of most of the extraction issues of the higher pressure.
The rest is an engineering exercise. Your right if I grab my old AR-10 jam a 277 Fury barrel into the existing barrel extension and start blasting your going to have problems. It was designed for a steady diet of ~62ksi generate loads not 80ksi generated loads. Things are going to likely wear faster or even break after much lower rounds counts. But that is only if we put this new cartridge in a rifle not designed for the new cartridge. If they design the rifle from the ground up to deal with these loads then its a non-issue assuming the engineering is done correctly. There is nothing inherent about going to 80ksi that is going to make building a reliable semi-auto problematic, assuming the hybrid case has dealt with the obvious ammo/pressure issues. There are going to be barrel life issues (due to the combined elevated temperature and velocity) but the action simply need to be designed for the forces involved.
243winxb
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The hybrid case gets rid of most of the extraction issues of the higher pressure.
SIG patent application entitled MULTI-PIECE CARTRIDGE CASING AND METHOD OF MAKING, note that the patent application also describes a multi-piece pistol cartridge case. SIG Cartridge Case Patent Application 2019, US20190226817A1.pdf
The alloys used in the case head and body can be very different then brass that we are used too. The patent is saying pressures as high as 120,000 PSI for rifles.
See page 7 at link above.
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SIG patent application entitled MULTI-PIECE CARTRIDGE CASING AND METHOD OF MAKING, note that the patent application also describes a multi-piece pistol cartridge case. SIG Cartridge Case Patent Application 2019, US20190226817A1.pdf
The alloys used in the case head and body can be very different then brass that we are used too. The patent is saying pressures as high as 120,000 PSI for rifles.
See page 7 at link above.
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Crosshair
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Just reading the Guns America article has all sorts of alarm bells going off in my mind about the practicality.
First off, what is the cost of these cases vs conventional one-piece brass? 120mm shells you can get away with that fancy stuff because you arn't firing it off at 600 RPM.
How well is a 3-piece case going to reload? How resilient to case seperation will even new brass be when going through an autoloader?
Why not just use a completely steel case?
Barrel life claims I simply don't believe at this point.
Sounds to me like an investment to write themselves a blank check by locking people into one amunition supplier.
Extremely sceptical. Time will tell what is going on. Is this going to be another case of firing million dollar missles at $10 tents?
First off, what is the cost of these cases vs conventional one-piece brass? 120mm shells you can get away with that fancy stuff because you arn't firing it off at 600 RPM.
How well is a 3-piece case going to reload? How resilient to case seperation will even new brass be when going through an autoloader?
Why not just use a completely steel case?
Barrel life claims I simply don't believe at this point.
Sounds to me like an investment to write themselves a blank check by locking people into one amunition supplier.
Extremely sceptical. Time will tell what is going on. Is this going to be another case of firing million dollar missles at $10 tents?
But will it kill Elephants and Cape Buffalo? What about grizzly? I guess I just don’t understand. That’s a lot of hype from them and I’m not seeing it anywhere as a good trade to what’s already out there. A proprietary cartridge in a proprietary rifle. That always seems like the fastest way to a short production.
The military doesn't reload for the common grunt, so that's not even on their radar. Cost? It's free money.
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