.277 SIG Fury Demystified

in Ammo Tests, Authors, Levi Sim
.277 SIG Fury Demystified
SIG’s new cartridge, the .277 SIG Fury, has just about broken the internet with all kinds of wild speculation. Here’re some of the facts. (Photo: Levi Sim)

Earlier this week, SIG introduced their new Cross rifle to much acclaim. They mentioned that it’s chambered for .308 Winchester, 6.5 Creedmoor, and .277 SIG Fury.

Well, the speculation about this mysterious .277 SIG Fury has practically broken the internet. GunsAmerica spoke directly with an authoritative representative from SIG to get the scoop and figure out exactly what’s going on with this cartridge.

.277 SIG Fury Demystified
The .277 Fury is a 6.8mm cartridge based on .308 WIN. (Photo: Levi Sim)

NOTE: Our Editor, True Pearce, took the Cross rifle and the new Fury ammo on an elk hunt this Fall and we used some of his leftover ammo for these photos. Please note that these are pre-production cases and they don’t even bear a headstamp.

Is the .277 SIG Fury a Magnum?

The short answer is no. It fits into a short action rifle and has the same head diameter as a .308.

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.

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.

.277 SIG Fury Demystified
The Fury’s hunting projectile, a 140gr bullet, will fly at 3,000 FPS from a short 16″ barrel. (Photo: Levi Sim)

This is significant because this kind of speed is usually only possible from longer barrels and magnum rifles. While some claim handloaded speeds with 6.5 Creedmoors of over 2900 fps with 140 grain bullets, the truth is that they are shooting 28-30 inch barrels or are not following actual published load data and are far exceeding safe pressures (We might know some guys).

.277 SIG Fury Demystified
SIG’s new Cross rifle with a 16″ barrel.

SIG’s launch of the Cross rifle is targeted squarely at hunters and long-range shooters. They even offer it from the factory with FirstLite’s popular Cipher pattern. That gun with a 16″ barrel and chambered for .277 SIG Fury weighs just 6.2 lbs, and that’s very attractive when you consider that velocity.

What’s Different About This Case?

The .277 SIG Fury is a three-piece cartridge. The brass part of the case encompasses the body, shoulder, and neck. The base or head of the case is stainless steel and is where most of the pressure happens. The third piece mechanically bonds the stainless base and brass body together inside the case. SIG says, “We see this as the technology of the future.”

Putting a steel head on a brass case is not a new idea, but it has never been mass-produced. “We’ve been targeting a better way to manufacture it,” SIG’s representative says.

.277 SIG Fury Demystified
Fury cartridges are the first three-piece rifle cartridges produced in commercial quantities. Left to right: 6.5 CM, .277 SIG Fury, .308 Win. (Photo: Levi Sim)

Steel is much stronger than brass so this case can withstand higher pressures without being as thick as brass would require. It’s much lighter, making this case weigh significantly less than brass casings of similar loads. Soldiers who pack this stuff around by the ammo can-full will appreciate that.

.277 SIG Fury Demystified
A standard bolt for 6.5 CM or .308 will fit the .277 SIG Fury. The cartridge shoulder dimensions, however, won’t let the SIG Fury fit in the chambers of those rifles. (Photo: Levi Sim)

The case head is the same diameter as .308 and 6.5mm Creedmoor cases. The case has a similar OAL to a .308.

.277 SIG Fury Demystified
Top: .277 SIG Fury. Bottom: .308 WIN. (Photo: Levi Sim)
.277 SIG Fury Demystified
Top: .277 SIG Fury. Bottom: 6.5 CREED. (Photo: Levi Sim)

All these comparison photos should give you a good idea about the case. Once the SAAMI registration is published we’ll have exact dimensions.

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.

.277 SIG Fury Demystified
The stainless steel head on this cartridge makes it lighter and strong enough for 80,000 psi. (Photo: Levi Sim)

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 SIG Fury Demystified
The heads are all the same size but don’t ask your gunsmith to rechamber your rifle. .277 SIG Fury in the middle, 6.5 CM on the left, .308 Win on the right. (Photo: Levi Sim)

.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.

.277 SIG Fury Demystified
Top to bottom: 6.5 Creedmoor, .277 SIG Fury, .308 Winchester. (Photo: Levi Sim)

SIG emphasized that any forthcoming products won’t be existing chamberings. “Future cases using this technology will be a SIG Fury caliber. All of those cartridges will be proprietary SIG.” There won’t be a 6.5mm Creedmoor with this casing because they want to ensure that nobody loads this high-pressure ammo in actions that aren’t designed for it.

.277 SIG Fury Demystified
.277 Fury fits 7.62x51mm mags. (Photo: Levi Sim)

It does feed perfectly from existing AICS magazines.

SAAMI Registration

The .277 SIG Fury was filed with SAAMI in summer 2019 and the registration is expected to be completed early in the first quarter of 2020. Since it’s not finalized with SAAMI, we don’t have the exact specs and tolerances, yet.

.277 SIG Fury Demystified
Top: .277 SIG Fury. Bottom: 6.5 CREED. (Photo: Levi Sim)

SAAMI, the Sporting Arms and Ammunition Manufacturing Institute, is “tasked with creating and publishing industry standards for safety, interchangeability, reliability and quality, coordinating technical data and promoting safe and responsible firearms use.” All cartridges you buy commercially meet SAAMI specs and you can reference their specs for your own reloading.

What Does SIG Proprietary Mean?

This is a SIG designed cartridge that doesn’t fit any other chambering. Some speculation was that this would fit in a regular 6.8. It won’t. Sig has registered this cartridge with SAAMI and fully expects other manufacturers to produce ammunition and rifles chambered in their proprietary chambering. No royalties will be required. Everyone will benefit from the commercialization of this cartridge.

Barrel Life

With high pressures and special powders, the barrels have got to be wearing out like crazy, right?

Testing is still being conducted on barrel life, and most of the focus has been on the full-auto belt-fed machine gun barrels SIG is pitching to the military. They have done lots of testing on the bolt guns, too, but SIG isn’t ready to release numbers quite yet.

.277 SIG Fury Demystified
With new powder blends, 3,000 fps doesn’t mean it’s burning up barrels. .277 Fury side-by-side with 6.5 Creedmoor. (Photo: Levi Sim)

They told us the preliminary numbers, though, and we had to ask again to clarify because it didn’t sound possible. We can say that with specific barrel coatings the barrel life with the .277 SIG Fury is better than the speculation in the forums and better than you’re imagining.

Way better than you’re imagining. Can’t wait for SIG to finish testing and release the final numbers.


SIG will have reloading supplies for Fury ammo in the future. Their priority right now is in winning the government contract and launching the ammo commercially.

.277 SIG Fury Demystified
Top: .277 SIG Fury. Bottom: .308 Win. (Photo: Levi Sim)
.277 SIG Fury Demystified
6.5 CM on the left, .277 SIG Fury in the middle, .308 Win on the right. (Photo: Levi Sim)

What Happens to the SIG Fury if SIG Doesn’t Win the Military Contract?

SIG assured us that they are “all in” on this cartridge and concept and that regardless of what the military does that they will be producing and creating other calibers.

Their first goal is to finalize a manufacturing process that allows them to build cases in huge quantities and for as low of a price as possible.

.277 SIG Fury Demystified
(Photo: Levi Sim)

As part of their audition with the military, SIG has to produce millions of rounds of ammunition this year for testing. Their priority is supplying the military, of course, but they are making it available commercially no matter the military’s choice.

“We’ve already invested in this, in the machinery,” SIG told GunsAmerica. “We are going forward with this no matter what happens with the military.”

.277 SIG Fury Demystified
(Photo: Levi Sim)

What’s It Going to Cost?

SIG doesn’t know yet but they know that to succeed commercially that it can’t be way more expensive than other hunting ammunition on the market. Currently, they’re machining the case heads but have several other technologies that they’re investing in that could make the cases much less expensive.

And if the military adopts it, then it should become relatively inexpensive due to the quantities that will be manufactured.

.277 SIG Fury Demystified
(Photo: Levi Sim)

What Ammo Will Be Available?

We do know that there is going to be 135-grain match ammo and 140-grain ammo right off the bat. These photos are all the 140-grain hunting round. SIG expects a plethora of bullet options to follow as well as other ammo manufacture’s to load for the round.

How Does It Shoot?

Preliminary tests are excellent. Our Editor, True Pearce who has hunted with and shot the rifle and ammo says that “it exceeded his expectations in a hunting rifle.” Currently all of the Cross rifles chambered in .277 SIG Fury are prototypes but you can expect GunsAmerica to do some accuracy testing and report on it as soon as production guns are available. It doesn’t do anyone any good to report on a non-production prototype rifle’s accuracy that will be different than the finished product.

The Cross Rifle

The Cross rifle — which is a crossover between tactical and hunting — is currently the only rifle available for the .277 SIG Fury ammo. It is the only rifle that can shoot it, and SIG developed the rifle from the ground up for this revolutionary cartridge.

.277 SIG Fury Demystified
The Cross rifle has a monolithic receiver engineered to handle high pressures like a boss.

Development started four or five years ago on the rifle and it has been extensive. Everything in the rifle was designed and manufactured by SIG. The action and trigger (parts you can’t see from the pictures) are different from a design perspective than anything else available on the market. Obviously there are similarities between any rifle. They all have a stock, a bolt and a barrel but the way it works is unlike anything else out there.

Unfortunately, rumor has it that the production version won’t have the dust cover.

.277 SIG Fury Demystified
Although many controls are familiar to AR owners, this gun is aimed at hunters in a big way.

MSRP for the Cross rifle is $1,779, but you’ll find it at stores for the minimum advertised price of $1,599.

.277 SIG Fury Demystified

About the author: Levi Sim is an avid hunter, and an increasingly avid shooter. He strives to make delicious and simple recipes from the game he kills. He makes a living as a professional photographer, writer, and photography instructor. Check out his work and he’d love to connect on Instagram: @outdoorslevi

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  • Lane Crawley February 22, 2023, 9:50 pm

    The US Military has done some interesting things in the Past but this will go down as one of the worst.
    A super high pressure cartridge with more than DOUBLE the Recoil of the current military issue 5.56 cartridge. Most recruits have never shot a rifle and out of all the Cartridges the Military could have chosen they pick a Heavy, High Recoil, Limited Mag Capacity Cartridge.
    Every Weapons Expert in the US is scratching their Head, What the Hell is the Military Doing???
    The 6.2mm ARC Cartridge by Hornady is the Perfect Low Recoil, Light Weight, High Magazine Capacity, 1200 yard Range Cartridge with 50% less recoil than the 277 Fury Cartridge. As far as a battle cartridge for our Military is Concerned this will go down as one of the biggest blunders and fleecing of the US Military (by SIG Sauer) in History.

  • George Fournier January 2, 2023, 7:12 am

    80,000 PSI to get < 2800 ft-lbs ?? I get 2900 ft-lbs from a 20” 308Win with an all copper 150 gr 308 BD2 bullet made by Badlands Precision with a G1 of 0.515 by simply using Lapua Palma brass and 49 gr of Leverevolution at s much more reasonable pressure snd shootable from the AR10. Out does this 277 Fury.

  • Arty September 12, 2022, 1:22 am

    My first thought..a Civilian 270 Winchester, or a 243 would work just as well as this 277 Fury. They are pushing a round fast out of a 16″ barrel.. while M4s use about a 14.5″ Barrel. So … lengthen the Barrel, shorten the lifespan of said Barrel, increase the recoil and noise. . Shouldve went with one of the already existing rounds. Why couldnt they like stick with; 224 Valkyrie, 6.5 Grendel or creed, 308 barrel so they can also use 7.62×51. The 270 or 243 Winchester rounds. 277 Furry is a dumb idea with so many other very close rounds. I have a 308 bolt action, I dont need a 277 Furry bolt action. Mine will work just as good.
    This 277 is a Foolish round that needs scraped

  • Tommy R Walker June 17, 2022, 12:51 pm

    I wonder how the new shell tech will handle reloading? Will separation end up being a factor after a couple of times reloading?

  • TkG May 3, 2022, 3:14 pm

    Im surprised there was no interest in a saboted sub caliber .308 loading a la the Remington Accelerator. Seems like it would check most of the boxes.

  • Nathan April 21, 2022, 12:54 pm

    Just read that SIG has won this competition. A few things I haven’t seen discussed much or at all:
    1. 80K PSI out of a 16″ barrel.. the noise and percussion.. oh, hurts just thinking about it. Hopefully the picture I saw that had a suppressor-looking muzzle device is how they will be delivered, and is not just a marketing image.
    2. Barrels are going to wear out quickly unless there is some secret sauce Sig has come up with. I suspect they’ll enjoy the follow on business for replacement barrels.
    3. Recoil is going to be significantly stronger than the M4, which will be an additional training point. I doubt we’ll see Drill Sergeants shooting them off their forehead to show the new recruits how they shouldn’t be scared to shoot them like I’ve seen with the M4.
    4. 2lbs of extra weight is a lot when you’ve already got about 65 lbs of gear with you. I haven’t heard what size magazine these will have (I’m guessing about 20 rds per magazine), but that doesn’t sound like a good trade off to me.
    5. Stronger recoil and less per magazine (my assumption) means less volume of fire. In my combat experience (not an infantryman, so it’s limited) and based on war documentaries I’ve seen, precision fires at distance is not the norm. At close ranges where accuracy really does matter, the 5.56 is sufficient (but I’ll quickly admit probably not ideal). At longer distances, usually its suppressive fire, which accuracy and hits don’t matter as much. Long range hits are generally left to the snipers, squad designated marksman or crew serve weapon. I noticed the optic is a 1-8x, so at least they thought that aspect through.

    Don’t think its the choice I would have made, but certainly hope good comes of the decision! I’d like to have seen a 87-95grain 6mm projectile shot at least 2900fps, but I’m just a random guy posting on the internet and my opinion means nothing, haha.

    • Michael October 26, 2022, 11:04 am

      Totally agree. 6.5 grendel TIP in shortened .223 case and faster powder. 90-110 gr ammo per military spec Geneva FMJ steel core and 2800 fps out of 16 with no dangerous pressure technology.
      With dangerous high pressure you could get 3100 out of it… maybe 3300

  • Harv February 23, 2022, 8:36 pm

    At 80000 psi the heat generated has to be much higher . They must have an awesome type coating in barrel to preserve the rifling.
    The military wouldnt adopt if not a high round count .

  • PAUL SILVA February 9, 2022, 11:54 pm

    lets convert everything to a three piece case, and add the secret souse powder to some of our old favorites, how about a 178 gr on top of a modified 308, how fast can we go with a 26” barrel?

  • Jormundyr January 19, 2022, 1:23 pm

    My first reaction was laughing. Seriously, this is a magnum cartridge. Need I remind you that a bunch of pansy generals complained about the normal pressure 30-06 (.308/7.62×51), back in the day. How do you think this is going to go in say a few years. After all those girls they have been letting into combat units actually have to use this rifle. The hilarity that shall ensue shall be glorious!

    As already mentioned, there are plenty of options that require no new expensive rifles, or cartridges that would suffice for the “complaints” raised. They could use 224 Valkyrie and have a significant upgrade using existing platforms. That is sticking to one that is been commercial for years now and extremely popular. But for the sake of brevity and that it has been just about covered, I am going to close with the following.

    It is Sig Sauer, economical is not in their vocabulary.

  • KMacK January 14, 2022, 4:50 pm

    The Generals should be prohibited from ordering weaponry, cartridges, or anything that a real warfighter needs to use and depend on. Let the grunts do the ordering. Set up committees of veterans and active military and let THEM decide on what the Army orders and from whom.
    My reasoning for this is due to my service in Vietnam, armed with Stoner’s abortion which nearly got me killed twice by failing in combat (despite being clean as a whistle prior to the engagement). To this day I will not have any Stoner-designed weapon in my collection. The man may have been a genius, but he was an idiot when it came to arms design. Even today, soldiers in the sandbox have to be more aware of the state of their weapon than their surroundings since even now a small amount of sand or dust can render an M-4 or M-16 into a funny-looking club. And here we go again, the idiots with stars are ordering things that will get the lowly warfighters killed, just so they (the Generals) can say they’re staying current and up-to-date. Makes me glad I’m OUT and plan to stay that way.

    • Joel April 22, 2022, 10:56 am

      KMacK: You nailed it! Purely experimental,expensive and unnecessary. Barrel life and potential problems with a 3 piece case seams like a recipe for disaster. Many good rifles and excellent rounds that have been proven over the years and yet the generals seem determined to spend taxpayer money on an experiment. This article was written as a cheerleader statement for Sig, no technical information, no performance data. Obviously Gunsamerica is just trying to generate enthusiasm for the next big thing.

    • Arty September 12, 2022, 1:10 am

      Thank you for your service, and yes I fully agree that the military needs a better counsel when it comes to new procurements

  • 1SG W. Scott McDonald January 5, 2022, 3:20 pm

    Having trained soldiers over 19 years in the use of small arms, the emphasis in a new rifle and a more powerful cartridge to allow the vast majority of them to accurately engage enemy targets beyond 500 m is questionable. It would make more sense to use existing M110 (AR10) with suitably adequate variable powered scopes (3-12 power, Illuminatable, “Christmas tree” reticle) and armor piercing 7.62-51 ammo (enhanced). We are still in NATO and should retain compatible ammunition.
    The weight savings issue would be addressed through higher hit probability and using less ammunition. Enhanced armor piercing 7.62-51 is more than capable of penetrating individual body armor out to 800m, which is the about the maximum effective range of an average rifleman with the M110 described above in combat conditions.
    Bottom line, I don’t buy the Army’s justification for new ammo and a rifle/SAW for it. Spend the money saved and put it into ammunition and additional time to develope/maintain proficiency with the soldier’s issued weapon.

  • P. Cameron November 29, 2021, 1:16 pm

    More ridiculous investment in the least casualty-producing part of warfare. You could get largely the same effect cheaper by re-fielding 7.62×51 with the improved case head/polymer cases True Velocity is making, which is what I believe this shindig is really about. Notice everything is backwards compatible with .308.

    Nobody but designated marksmen and snipers will appreciate the performance of this caliber. On the other hand, everyone will despise the added weight and bulk once the novelty wears off, especially SAW gunners. Real McCoys like Chuck Pressburg and Jose Gordon (both Rangers with decades of service time) break this down phenomenally, it’s about high round count and rapid follow-up shots NOT kinetic energy and ballistic coefficient. Volume wins over accuracy.

    If anything, we should be looking at hybrid PDW calibers like Colt’s 5.56×30 MARS. FN’s 5.7×28 and HK’s 4.6×30 are anemic, but there is a sweet spot for a 0-300 meter infantry cartridge that’s exactly as large as it needs to be and nothing more. Smaller cartridges translate to less weight and bulk for the same ammo count. We could have slimmer magazines which means more rounds carried in the same cube space and a slicker overall profile of our carriers, meaning a faster soldier. Being able to maneuver faster than the enemy is paramount.

    As for the GPMGs and DMRs out there, we should start with a .308 case, then balance the weight and diameter of the projectile to acceptable 800 meter performance. We attempted this with 6mm SAW during the 70s and the round proved satisfactory, but it was abandoned for logistical reasons when an “improved 5.56″ was promised. It turned out to be a turd of a round named M855. I’m a big fan of .224 Valkyrie, which is a heavy .224” bullet inside a 6.8 SPC case. Taking that concept and applying it to a .308 case would yield us incredible flexibility with high velocity AP ammo and low-drag rounds for range.

    Anything that can’t be handled by either flavor of improved 5.56 should be handled by a force multiplier wielded by the squad grenadier, such as Raytheon’s “PIKE” offering. It’s a laser-guided 40mm grenade with a range of 2,000 meters, capable of being fired from an M320 or M203. If the industry were to follow suit with their own take on compact infantry-guided explosives, the squad would have total supremacy with less reliance on air support, though certainly greater use of small drones equipped with similar compact explosives for different tasks should be deployable from FOBs.

    There’s a right way to give our soldiers “overmatch”, as if we didn’t already have it. This fantasy that we’re all going to die if we don’t go back to battle rifles is going to get our soldiers killed in silly ways.

    • John D December 25, 2021, 6:47 am

      If you take a 308 case and shorten it to, what looks like 1.98, then push the shoulder forward to @1.60, blow the case out to about .455 and shorten the neck somewhere in the .290 range and add a 30 degree shoulder, you have this cartridge. Wouldnt be hard to get close to 3K fps from a 16 inch barrel with a 140, when you reduce the pressure that much, then re-increase it with case capacity. Maybe not quite the same, but close. Just another gimmick cartridge…

    • Vojtech January 13, 2022, 2:03 pm

      Please, can you mention source where Chuck Pressburg and Jose Gordon mention rapid followup shots And high round count? Thank you.

      • Red January 30, 2022, 10:02 pm

        I think I remember exactly that discussion from one of the P&S podcasts.

  • Wayne August 8, 2021, 11:06 pm

    Sooo if I get the cross rifle in 277 fury it will shoot the 6.5 and the 308 ammunition…. Win win as far as I can tell …. So now I wonder what it’s going to cost?

    • Sam December 17, 2021, 12:53 am

      Dude please don’t do that, because if you try to shoot a bullet that is 7.62 mm (308) through a 6.8mm hole you might just kill yourself, and shooting the 6.5 mm might work but your accuracy would suffer because of the lost gases

    • John D December 25, 2021, 6:37 am

      Wayne… I hope you don’t own a firearm…

    • KMacK January 14, 2022, 4:54 pm

      Cost? Sigs are built like Rolls-Royces…and cost appropriately. Why not something less spendy and just as good, only lacking the fancy name?

    • Survival gear December 13, 2022, 3:42 am

      Won’t work with either. It more like you going to buy a 277 rifle and then won’t be able to get ammo from anyone but sig(for a high price) and then unless you’re reloading it won’t be available literally anywhere.

  • Nate Dogg July 4, 2021, 1:10 pm

    This new cartridge is meh. A little lighter cartidge casing capable of very high pressures, but only needed due to leadership with obsession with overmatch from short barreled rifles. The 6.5 Creedmoor is just as good for most and already exists. Personally the US military has screwed up massively, as the leadership have historically proven to mess up small arms purchases and cartridge selection. This goes back to musket times, the only really good rifle design selection, for the time, was the M1 Garand, but it was bought with the wrong bullet.

    There is no magic bullet that can do everything, but there is an optimal one for a general purpose cartridge and a 6.5mm bullet based on the in-service 5.56mm/7.62mm EPR bullet design would more then likely meet the needs of the military now and in the future. Osprey Combat developed the 6.5mm Super Z and using a brass case that while heavier than 5.56mm, is much lighter than a 7.62mm NATO, and could meet the military’s needs at much lower cost. The 6.5 Super Z matches or exceeds the 7.62mm NATO capabilities at a reduced weight with much less recoil. It also fits in the action of the M16/M4 and new optimized uppers could be rapidly procured to replace current 5.56mm inventory.

    Imagine the firearm capability improvement of an entire infantry squad equipped with 6.5mm Super Z firearms and optimzed optics. No need for heavy 7.62mm class firearms or very expensive super weapons requiring very pricey firearms to fire expensive high pressure cartridges.

    Don’t get me wrong the M16/M4 needs to be replaced with piston-rod or similar operating system, but a new .277/6.8mm in my opinion is the wrong choice. Check out this link. It is a great off the shelf designbthatbhas been well tested and if there is military with a better general purpose cartridge design when all factors are taken into account, I’d like to hear about

  • Jim Goerner April 25, 2021, 3:08 pm


    Well, in the article there is told that .277 SIG FURY would be “no magnum”. This joke is good. But I do not laugh not at all: It is the same as with good old 8X68S that IS magnum eventhough the case is rimless. You must know that it is fakenews that a cartridge that does not have a rim at its base would be “no magnum”. Ts …… Listen! The brandnew .277 SIG FURY hab been developed for the US military for their future battle rifles and the maximum pressure of this caliber is 80’000 psi so I think that tells much enough about whether this cartridge is magnum or not n’ est-ce pas ……………..

    Best Regards from Sunny Osnabrück*!


    PS The German Military will choose different ammunition, perhaps 6.5 mm RPM or 6 mm Creemoor, let ‘s wait and drink coffee to see what happens ……………………………….

    *located in the far North/West of Germany, right on the line Hannover─Amsterdam

  • Wade Garrett October 6, 2020, 6:32 pm

    would like to see the 277-sig-fury and the brakdown on and the rage detals on it

  • Dean Dong July 25, 2020, 12:42 am

    I’ll take one in a lefty! Sig is the shit for their innovative efforts and pretty damn high standards of quality.

  • Mike Owen May 7, 2020, 7:53 pm

    This is what I love about this industry. Innovation is the true cause of curiosity for gun gearhead. As soon as we start to get bored out comes something new and makes us imagine what else is possible. I bow to the industry innovators. Keep looking forward and imagine no obstacles that cannot be tackled.

  • 22 Chuck March 21, 2020, 1:03 pm

    For those interested in saving money-just use your Covid-19 stimulus $$ and get a new rifle. Only problem is this wont be available in any quantity for 1+ yrs, I bet.

    New design will bring new problems but w/ the govt contract at stake SIG will do all they can to fix em, first.

    Wonder what it will look like in 5-10 yrs as they plan on other guns/calibers, it sounds like.

  • Rock Her February 4, 2020, 2:20 pm


    How long is a brass case good for due to possible rusting in the head area from dissimilar metal?

  • Carlos February 2, 2020, 12:07 pm

    What does Sig Sauer mean by “maintaining good accuracy”? What is their definition of “good accuracy”?

  • Ward February 1, 2020, 11:03 pm

    .277 in = 7.0358 mm.

    So it’s a 7 – 08 with a slightly larger case volume. Plus higher pressures and a stainless base to withstand those pressures.

    Will that really make a difference?

    • Casey Chadwell February 5, 2020, 11:14 am

      I’d say 3000+ fps out of a 16″ barrel is a significant difference.

    • Brent February 6, 2020, 7:16 pm

      .277 is a 6.8 mm
      .284 is 7mm
      so it’s a 7-08 necked down to 6.8 with just a little bit of capacity added

      • wgars433 August 14, 2020, 7:10 pm

        Brent… I believe you’re correct and incorrect at the same time.
        My calculator says:
        .277 cal. = 0.70358mm, which is a tight 7mm, but 7mm nonetheless.
        .284 cal. = 0.72136mm, which is also 7mm, but considered the ‘official’ 7-08.

        • CJ September 10, 2020, 7:06 pm

          Actually Brent is right on both accounts. The reason is because what different designations are actually referencing.

          When reference is in “Calibers”, what is being referenced is the Groove and bullet diameter.
          When reference is in “millimeters”, what is being referenced is the bore diameter of the barrel (i.e., the diameter at the lands, not the grooves.

          To give you an example, lets say you have a 6.5 Creedmoor. The bullets themselves are .264 caliber (or 6.7mm) The bore of the rifle at the lands is what is 6.5mm (or .255″)

          A rifle that shoots a .284 Caliber (or 7.2mm) bullet is a 7mm rifle because the bore size is 7mm (or .2755″)

          A Rifle that shoots a .277 caliber bullet will have a bore size of 6.8mm (or .268″)

          Just to give you another example that you will likely be familiar with is the .308Win. This is also often referred to as a 7.62 NATO since they are virtually identical in size (just a tinny difference in head spacing specs)..,.,
          Well .308 is really 7.82mm. The bore however on pretty much everything that shoots a 30cal projectile will have a 7.62mm bore and hence where the 7.62 reference comes from in the NATO size specification of 7.62 x 51

          So in the end, it just comes down to what the manufacture decided to reference when they gave it the relative size designation.
          Hope this helps you (or anyone who reads it) better understand the difference between references when in Metric or in imperial classification.

          • Joe Allen December 11, 2020, 6:10 pm

            No, it didn’t help. It added to my confusion. How can a 7.2mm bullet fire from a 7.0mm barrel. Im not very knowledgeable about firearms. What am I missing?

    • Harv February 23, 2022, 8:17 pm

      The 7mm-08 uses a .284 diameter bullet.
      The European 7mm also use same .284

  • Valorius January 30, 2020, 1:11 pm

    What is barrel life going to be like at 80,000 psi? What type of steel can withstand that pressure for a useful service life?

  • William Lindley January 25, 2020, 1:29 pm

    Caliber sounds cool. Would live to see a more traditional stock though. Just not my style..

  • Siv Pot December 31, 2019, 3:26 pm

    What’s the twist on the .277 Fury barrel? Hoping it’s at least 1:9 for use with the 170 gr EOL Elite Hunter.

    • RM November 9, 2020, 7:25 am


  • Craig wilson December 28, 2019, 5:22 pm

    Where can we get one of the .277’ at

  • GERALD MICHRINA December 28, 2019, 9:41 am

    I guess I am suprised at the military mindset of having such a one off unique cartridge. Faster I get but what if supplies are cut off from front line soldiers, it would seem short sighted to have a clambering that gou couldn’t get ammo for from some other NATO partners. Perhaps that isn’t how it works but unless this also becomes a NATO clambering you could find yourself cutting off from command with no alternative solutions.
    OR, maybe SIG is playing this as the first step to be a NATO chambering.

    • Joshua January 15, 2020, 2:52 pm

      It’s not SIG, it’s the US Army.

      They want to replace the 5.56 and M4/M249 with their own custom built .277 caliber bullet. They’ve left it up to the individual companies to come up with the case and gun to fire the bullet.

    • Carlos February 2, 2020, 12:10 pm

      They have to start somewhere. If they had your way of thinking and never explored new calibers and weapons systems we would probably still be using the .30–06.

      I’m more surprised that they are actually willing to explore new calibers as a replacement for the current issued calibers.

  • Craig December 25, 2019, 1:28 pm

    Don’t forget about the left handed people, how about Sig?

    • Cajun Exile January 31, 2020, 11:22 pm

      “Don’t forget about the left handed people, how about Sig?”

      Indeed! (bump)

  • Wade December 24, 2019, 12:03 pm

    The question I have is what is the muzzle blast like? 80,000 psi out of a 16″ barrel, would imagine that baby is loooooud! Could be wrong but don’t think so…

    Sig states they expect others to load the round. Don’t imagine that would be possible with any cases but theirs. Wonder if they plan to sell the cases to other manufacturers.

    Would be interesting to marry this round/load level with the new polymer cases that have been showcased in Guns & Ammo recently, cannot remember the name of the developer. Wonder if those cases could handle the pressures involved.

    No question there will be military applications, there will also be interest on the civilian side but i’m not sure to what level. I don’t see a huge rush of hunters going for it, but the PRS crowd should be interested.

    Will be interesting to watch.


    • Shannon Nunn January 15, 2021, 10:55 pm

      The powder will most likely be a fast burning powder like a pistol powder that will fill the case burn very fast and increase initial pressures but reduce pressure at the muzzle due to burn rate… Just a guess

  • mark December 24, 2019, 9:55 am

    Appears they reinvented the proven 270 Winchester by jacking up the pressure to 80,000 psi, which is so high it needs a special steel case and likely creates other problems that will take years to resolve. I also note that Hodgdon’s reloading data shows I can already shoot a 120 gr bullet from a 270 Winchester at over 3,100 fps at 60 Thousand psi, though admittedly that is from a 24″ barrel. (say, around 2,800 fps from a 16″ barrel?) I suspect this technology also pushed up the recoil but i’ve seen no data on this. (and the 270 Winchester has a very reasonable recoil). So, 1) I’m not really saving any weight over the proven 308 or 270 cartridge and may need a heavier rifle for both the pressure and recoil,. 2) Small velocity increase as a result of very high pressures, and 3) Requires proprietary technology likely requiring years of working through problems, meaning costs are much higher. For me, the quest for the Holy Grail continues.

  • Lamce December 24, 2019, 3:58 am

    Oh hell, I thought they were talking about a Plymouth Fury!

  • Howard Johnson December 23, 2019, 5:52 pm

    I like your writing–hojo

  • JCitizen December 23, 2019, 4:59 pm

    Oh geeze! I hate it when somebody comes out with something new that I just gotta have! I quit buying arms trying to save money, but now they’ve done it!! There go my plans!!

    I would think that a special formulation of the powder could achieve those velocities from a 16″ barrel or even a 10″ barrel, without so much pressure. All you need is a powder that does not spike in the pressure curve. The idea is to flatten the upper pressure curve so the bullet receives full acceleration through the length of the barrel. But I can see why SIG is doing it this way, because it guarantees proprietary equipment, that will lock SIG into the only provider. This kind of thing has been done before by the wildcatters on the east board of Colorado when wood chuck hunting. They were getting 3000 fps out of Thompson Center 10″ pistol barrels, but were using the shoulder stocks to steady the rifle. Something that is only easy to do with a TC brand because they have special dispensation on those laws from a Supreme Court victory against the BATFE. I have no idea where you get the powder, but they were calling it “hi-low” pressure powder – so it must have some dual quality to it, a lot like the way a grenade launcher works.

  • Jim December 23, 2019, 2:52 pm

    Here’s a link to what Textron’s developing for the contract. Note the case-less design for all 3 calibers (5.56, 6.5 and 7.62). While not a new idea, it’s design is definitely different.

  • J D Jones December 23, 2019, 12:59 pm

    Shades of French wildcatters using German steel case 8 MM cases for impressive ballistics. Dick Casull also used the same principal in bolt actions to embarrass the Magnums. While not make the case entirely of steel seems a legitimate question or is the current design a stepping stone.

    • JCitizen December 23, 2019, 5:06 pm

      I don’t know, but I’d think to keep the over all cartridge weight down, but still get a good gas seal, they’d have to keep it the way it is now. I would think this is patent protected, if that is possible, so they could corner not only a specific part of the military arms market, but the ammo market too.

    • Bob December 26, 2019, 2:11 am

      Got any links with more data on those french wildcats?

      • Jb January 6, 2020, 9:31 am

        A case head separation at that pressure would take your melon right off. It’s interesting for sure. I’ll take two.

  • Lew Dyte December 23, 2019, 12:07 pm

    Why don’t they make the entire case from steel? That’s proven technology and eliminates the issue of a joint between the steel head and brass body. Joins between dissimilar metals are problematic when exposed to moisture and over time.

  • Sam Vanderburg December 23, 2019, 11:38 am

    One of my first thoughts was, “How can I build one?” Well, that is a few years down the road. While it leaves the AR platform behind that has been so handy, the rifle offered is just the first step into firearms. If this takes, you will see several other manufacturers pick it up. And, it will be interesting to see what a company like Nosler will do with it…

  • Tom Reigle December 23, 2019, 9:40 am

    A very well written and thoroughly covered article on a completely new technology in firearms development. I am amazed at the different views and comparisons you have provided to differentiate this new caliber from its closest “neighbors”! What stopped you from splitting a casing in half lengthwise and showing us the casing interior and the “3rd” piece of that casing?

    Was there a reason why you did not include a full length photo of the off side of this rifle? And, since your editor has firsthand experience with using the rifle on an elk hunt,

    “NOTE: Our Editor, True Pearce, took the Cross rifle and the new Fury ammo on an elk hunt this Fall …”

    did he get his elk? Did he have any shots? Was there video made of the trip? Too many questions and so little time, eh?

    I am quite sure this isn’t the only article we will see from G A on this subject.

    Only one bitch – that nearly full screen popup from a concealed carry association is very annoying, even with my popup program in full operation! That is not like G A to do that and I hope that it does not become a habit for readers to put up with ….

    • Joshua January 15, 2020, 2:54 pm

      Third piece is a lock washer they use at the joint.

  • Kent Stonecipher December 23, 2019, 9:24 am

    What primer is being used to contain the pressure?

  • johnnyraygun December 23, 2019, 9:03 am

    Wasn’t it Weatherby who believed speed was the only thing that mattered?

  • OldOutdoorsGuy December 23, 2019, 8:54 am

    @ Ray Robinson – I agree with you on many levels, Ray, it is technology that is long overdue and barely starting and guys like you and I will never reap the benefits of these radical upgrades in shooting technology. And it is not altogether the manufacturers’ fault nor is it simply a very slow revolution in design, research, and development. It is the extreme tunnel vision of those who like to blame the gun owners for every shooting and every psycho who believes that he will win a “golden summit” in the history of this world by taking a weapon and shooting up a schoolyard full of kids or a subway full of unsuspecting workers trying to get home from a hard day’s work.

    And now they are trying to abolish the laws of our great country one amendment at a time to further strengthen their warped and demented minds into thinking that THEY are actually helping the citizens of our great country to be SAFER??? The likes of a Clinton or a Pelosi mindset or any other variation of such a sick mindset should be made grounds for immediate isolation in some deep dark hole where they can wallow in their own deluded thoughts and allow this government to get back to governing again!

    Please accept my apology for temporarily derailing this thread but I am at an age now where I cannot sit back and watch the political carnage taking place in this country any longer. I was born during WWII and grew up poor but quite SAFE and FREE in my little piece of the world, being guided by my faithful parents who truly believed in RAISING kids, not simply HAVING them around the house. We should have had this technology years ago had it not been for greed and the importance of money and status to take precedence over the political “powers to be” in such a fashion that they now are a level ABOVE those who put them in office. They represent the VOTERS of this land, not themselves!! It’s high time we took stock of what we NEED and how we must conduct ourselves to get those needs met and ensure that we place those people in our government who will work hard and fast to properly address those needs and leave the nitpicking and the solving of the real “problems of the world” to the oldsters like us to talk about over coffee at the morning “round table discussions”.

    As Ray mentioned, “Oh, I have seen developments in my time but the future is always more exciting.”, I too have marveled at the sights and times we have spent travelling faster and going further than man could ever dream just a few years back. But it seems that we have lost our “focus” on what is important and what we really NEED to make us truly happy and secure in our lives. I am coming up to my 77th year soon and I am still living in a “poor” lifestyle as measured by what most people think they need to be “rich” today. But I have no stress. I have no immediate needs above a few minor medical “adjustments” to fix a couple of worn out joints in my “rode hard and put up wet” old body, but I still enjoy most of those pleasures which I have spent a lifetime enjoying, because most of them are still FREE for ANY and ALL of us to enjoy! I still love a crackling campfire in the late Fall when the air is crisp and the leaves are down and Winter is just a cold breath away. I still love the calls of the loon, the hoot of an unseen owl, the rustle of leaves and a quiet snap of a twig as an animal stirs within earshot of my presence. I get up early and stay up late just so I do not miss a single bit of what my life has been all about. How many can still enjoy a sunset or, better yet, the caliber of sunrises that we have down here on the “Forgotten” coast? My favorite mode of transportation, [since my legs have given me a warning that there is some work to be done], is my kayak, I have a lifetime pass to all of the state parks here in FL and also a Golden Age pass to all of the National Parks but I am still working on seeing as much of the beauty of our state parks here where I live before striking off to see those which are still on my “bucket list”.

    BTW, the bulk of my small collection of firearms was made by Sig Sauer and I applaud their fearless step into the “future” with all new technology and all new thinking and reworking of the firearms theory. They are properly “ignoring” those who would tear down a perfectly sound “Home” and try to rebuild something which will only bring satisfaction to a perverted few at the end of the day ……. Not since the evolution from flintlock to repeating rifle, from derringer to “six gun”, from black powder to “proprietary” powder blends, have we taken such a step into a whole new area of firearms technology. God willing, those who will govern the outcome of such studies will ensure that they are properly maintained and developed and allowed to be made available to ALL who desire to use this technology for a positive endeavor.

    • Lloyd A Smith December 23, 2019, 9:44 am

      Amen, Brother! I wouldn’t change a word had I written your comment. Well, maybe the lack of stress part. Seeing what the socialists plan for our nation does stress me to tears. What fools they are! And, they are leading the young down the gilded path with the promise of everything being free and we’ll punish the rich to pay for it. Our generation is rapidly declining and each of us must try to bring some common sense to the youth of America.

    • Carl December 23, 2019, 11:18 am

      Your words are on the money. I’m 52 and walk a similar path. Merry Christmas sir and thanks for sharing.

    • Shannon Nunn December 29, 2019, 7:21 pm

      Old outdoors guy,
      You are the same age my father would have been if he didn’t pass when I was a boy. He was an avid outdoorsman, Hunter and trapper and when we were the poorest, he was truly free. We spent everyday hunting and keeping up with our trap line. He was a marvel of a man. He was big hearted and a great father. Taught me to track desert deer and I am probably one of the few left that can hunt a deer in such a way. The old ways are passing us by and the collectivism of statism is catching us unawares.
      My father is probably crying in heaven seeing what has come if this nation and the mindsets of the younger generations. They have nothing, no father’s, no laws, no justice and very little education or freedom. It has all been replaced with an indoctrination of self hatred and anti-american ideologies.
      Pray we stop this while we still have time and breath on this sacred ground. Thank you for the words… We need more wisdom and experienced men expressing their thoughts on the state of affairs. May God bless and keep you.

    • RJ Biddulph January 7, 2020, 9:45 am

      Thank you, Sir. People like you give me hope for growing old.

    • Hugh Jardon January 8, 2020, 2:35 am

      I was enjoying this article and comments until some nincompoop (you) brought politics into it. Please ramble on free as can be, but do it somewhere else…nobody here needs to hear your rant. BTW, I stopped reading after your first paragraph and will not read your reply, so don’t bother.

      • PacosMojo March 2, 2020, 12:24 pm

        Oops, another Marxist outs himself at GunsAmetica!

  • don mccollough December 23, 2019, 8:27 am

    Can it be reloaded ?

    • JCitizen December 23, 2019, 4:38 pm

      As long as you had a tungsten die, I can’t see why not. Stainless will destroy a plain steel die.

  • triggerpull December 23, 2019, 7:31 am

    Very savvy move by Sig to release to the commercial market. This type of binary materials head/case body was offered years ago by power tech in the their 9mm cases–I waited and waited but they haven’t followed up with any other calibers.

    Sig is not going to make money on the ammo–they’re going to make money on the new proprietary receivers that will be an entirely new configuration. Unfortunately, this bolt action leaves out the immense existing fleet of AR’s–and even if something is eventually offered in the AR 10 world I suspect this cartridge will have difficultly gaining traction against what’s already available.

    Higher pressure is a cool thing that allows higher velocities. It also implies that when things go sideways–which eventually they will for whatever reason–that there will be higher pressures generated in catastrophic failures.

    • Big Al Robinson December 23, 2019, 10:52 am

      In fact, though higher pressures are generated, if the receiver is correspondingly made for those pressures (which it would have to be), then the whole scenario you paint is a wash.
      And the boys & gals at SIG aren’t stupid, this business and the U.S. are some of the most litigious in the world, they aren’t going to make something so poorly as to invite a lawsuit.
      Not to mention that many Military contracts CALL for a test to absolute destruction, so that they KNOW the parameters of catastrophic failure.
      In fact, part of SAAMI testing is a very high pressure cartridge, though I don’t believe that their test is to failure.
      So, it’s NOT very likely going to be like a bomb going off in your face, despite the pressures.

  • Dr Motown December 23, 2019, 5:20 am

    Well, now we know the name of the 6.8mm cartridge that the military wanted

  • Ray Robinson December 23, 2019, 4:40 am

    What makes me sad is new things have waited so long to come out. I am 76 and will probably be marginal in hunting ability by the time these things are common. Oh, I have seen developments in my time but the future is always more exciting.

    • NJ December 23, 2019, 8:45 am

      I’ve got a friend who’s dad told me something similar at your age. He turned 100 last month and lives alone in the same house he’s owned for 50+ years. He has quit hunting in the last few years, so I’d say you are down to around 20 years to plan for, maybe more since medicine is getting more sophisticated. Rock on.

    • Zupglick December 23, 2019, 8:52 am

      I’m with you. I’m wondering why we don’t have “rail guns” or chem powered lasers.

    • Eric Holder December 23, 2019, 11:58 am

      I don’t know. I watch a lot of black and white 50″s movies and when I see the women in that era compared to what we have now, I think the past was more exciting. Lol!

      • Carlos January 16, 2020, 1:15 pm

        I’m with you. The women in pre-Code 30s film are something else. We missed out.

  • Michael Maggio December 22, 2019, 7:38 pm

    Great article. You really got everything in it. Just got one question. Did they say anything about how much ammo will cost?

    • SIDNEY POST December 23, 2019, 7:37 pm

      Way too early for ammunition cost predictions this early into R&D. They did state it would be competitive with current hunting ammunition.

      I guess this means something around $1 to $3 a round. Will it be cheaper than 6.8SPC? Probably not but, if close it should fly off the shelves.

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