.277 Fury vs. 6.8 SPC: The Best of the Best of the Best? Sure

When the U.S. military requested a new cartridge for the battlefield, Remington and Sig Sauer responded with their own variations of .277” caliber cartridges. Remington’s 6.8 SPC didn’t make the cut. Sig went above and beyond, designing a revolutionary new cartridge and a rifle to boot.

Just because the Army opted to go with Sig’s .277 Fury doesn’t mean it’s going to be the best option for a consumer. In fact, there are a few reasons it may not be best for our guys in the field. Nonetheless, we’re excited to see the .277 Fury hit the market.

The 6.8 SPC and .277 Fury have many similarities, yet they serve two very different purposes. Each has strengths and weaknesses, which merits some well-rounded comparison.

If you want to explore the ammo we have in stock, click HERE. Otherwise, hang out with me while I tell you everything you need to know about the .277 Fury and 6.8 SPC.

.277 Fury vs. 6.8 SPC Caliber Comparison

If you’ve been keeping up with gun forums and small arms news, you’re probably aware that the U.S. Army awarded the Next Generation Squad Weapon program (NGSW) contract to Sig Sauer and the .277 Fury in 2022.

Sig Sauer developed an entirely new weapon system – the XM7 (previously designated XM5) and XM250 – to complement their new cartridge, and replace the aging M4 carbine and M249 SAW and their 5.56 NATO cartridge.

Remington had submitted the 6.8 Special Purpose Cartridge (6.8 SPC) decades prior in 2004. While the 6.8 SPC didn’t quite make the cut, it is still an impressive option for those looking to upgrade their AR-15s.

I’m going to discuss both of these cartridges in the following sections. But before I dive into them, it’s important to note that the .277 Sig Fury and the 6.8 SPC have two variations.

Sig developed standard and hybrid versions of the .277 Fury. The standard .277 Fury cartridge has a basic brass case with a max pressure similar to that of the 6.8 SPC.

The hybrid case consists of three separate parts: a stainless steel base, an aluminum locking washer, and a standard brass body. That’s the one that the Army is interested in.

At the time of writing, only one bolt-action 277 Fury rifle is available to civilians: the Sig CROSS. Sig has promised a civilian variation of the MCX-SPEAR, but we have yet to see it. (2025 Update: Sig now makes the MCX-SPEAR available to the civilian market.)

Back in 2004, Remington looked like it almost had a new cartridge contract locked down with their revolutionary 6.8 SPC design. But sadly, Remington dropped the ball. The military decided not to pursue the 6.8 SPC due to chamber pressure issues.

Remington ultimately fixed those issues, but by that time, the military was disinterested in the round. This left the civilian market with a few barrels stamped "6.8 SPC" and many more stamped "6.8 SPC II."

The following sections will give you a full 360 view of the 6.8 SPC and the .277 Fury Hybrid.

Cartridge Specs

The first place to begin your quest for understanding cartridges is the cartridge specs. Variations in bullet diameter, case capacity, and pressure give us insight into what these cartridges can do on the range, in self-defense situations, in hunting, and even in battle.

As you can see in our comparison, the .277 Fury is a bit larger than the 6.8 SPC (6.8x42mm compared to 6.8x51mm). But the most notable difference between the two cartridges is their SAAMI spec chamber pressures: 80k psi vs. 55k, respectively.

At the time of writing, the 277 Fury has the highest approved chamber pressure of all time, outstripping even the 338 Lapua Magnum and 50 BMG.

Its heavy pressure coincides with the .277 Sig Fury's higher muzzle velocity and energy than the 6.8 SPC could ever dream of. Sig easily defeated Remington in case specs, even in rifles with shorter barrel lengths.

The .277 Fury is a beast compared to the 6.8 SPC. But the 6.8 SPC was designed for America’s previous generation of weaponry (the M4), whereas the .277 Fury is tailored to the future and punching through modern body armor. It's un urprising that the Fury pushes the limits further.

Recoil

It is important to consider recoil before adopting a brand-new cartridge. A rifle with too much recoil is unpleasant to fire and indirectly affects accuracy and efficiency (realigning your sights with the target, flinching before shooting, etc.).

Muzzle velocity (feet per second, or fps), propellant charge weight, firearm weight, and bullet weight all determine recoil. Due to these factors, the military version of the .277 Fury has much more recoil than the 6.8 SPC.

The 6.8 SPC only has around 9 foot-pounds (ft-lbs) of recoil. The .277 Fury has about 18-20 ft-lbs (with some give and take depending on cartridge characteristics and rifle weight). That means the 6.8 SPC generates less than half as much recoil energy as the .277 Fury, which is pretty significant.

I wouldn’t necessarily recommend either of these options to novice shooters (the 5.56 is a popular choice for beginners for good reason). But if you’re planning your next upgrade, the 6.8 SPC's lower recoil ought to appeal to you.

Trajectory

I’ll come right out and say it: the .277 Sig Fury easily wins over the 6.8 SPC in terms of trajectory.

Shop 277 SIG Fury Ammo

Trajectory refers to how flat a projectile travels from barrel to target. The flatter the trajectory, the less the shooter has to adjust their sights for long-range hits. A flatter trajectory can also compensate for shooter ranging errors to some extent.

Trajectory is a really important aspect of long-range shooting. Marksmen generally prefer as little bullet drop as possible. The .277 Sig Fury has an excellent trajectory, even in conjunction with short barrels. It can maintain high velocities at ranges farther than most comparable rounds, including the 6.5 Creedmoor.

If you’re only interested in close-range shots or close-quarters battle (CQB), then the .277 Fury's flatter trajectory is a non-issue. And for medium range or designated marksman rifle (DMR) work between  200 to 300 yards, both rifle cartridges perform perfectly fine.

However, for long-range work, the .277 Fury is clearly the better choice.

Ballistic Coefficient

Both the 6.8 SPC and .277 Sig Fury have a pretty high ballistic coefficient (BC). For those new to the subject, a bullet's BC indicates how effectively it can overcome frontal air resistance and wind drift. Essentially, it tells us how aerodynamic the bullet is.

A bullet's profile, weight, and capacity for rotational stability all contribute to its BC. A higher BC indicates a bullet which conserves its momentum more efficiently. Put another way, a higher-BC bullet conserves a higher percentage of its velocity than a lower-BC alternative at any given distance.

The 6.8 SPC fires lighter bullets, which tend to be more easily blown off course. The .277 Fury fires heavier ones, which are inherently better equipped for resisting wind drift.

For example, the SIG Sauer .277 Fury Hybrid 150 grain polymer-tipped bullet has a ballistic coefficient of 0.500. In contarast, the 6.8 SPC Hornady Black 110 grain V-Max has a BC of only 0.370.

The .277 Fury, by design, typically has a higher B.C. than the 6.8 SPC.

Muzzle Velocity and Kinetic Energy

Shop 6.8 SPC Ammo

The .277 Fury easily beats the 6.8 SPC in muzzle velocity and kinetic energy thanks to its higher case capacity. In fact, the Sig Fury Hybrid beats most other popular options in its category thanks in part to its 80k psi chamber pressure.

A .277 Sig Fury 135 grain FMJ cartridge has 2,697 ft-lbs muzzle energy and 3,000 fps muzzle velocity. Meanwhile, Hornady Black 6.8 SPC 110 grain load only has 1,588 ft-lbs muzzle energy and 2,570 fps muzzle velocity.

The 6.8 SPC is perfect for those who want to go plinking or hunting. But for our guys on the battlefield – who must rely on ample downrange kinetic energy to defeat enemy body armor – the .277 Fury undoubtedly outperforms the smaller round.

Ammo and Rifle Cost/Availability

The winner of this category is the 6.8 SPC. Unfortunately, .277 Sig Fury ammunition is exceptionally challenging to find as Sig Sauer is the only company currently producing it. Although 6.8 SPC ammo isn’t overflowing from your local gun store shelves, it’s still a lot easier to find than 277 Fury.

The .277 Fury's recent introduction to the market limits its availability, at least in part. We expect demand (and by extension supply) of it to increase as time marches on.

Many firearm manufacturers produce all sorts of rifles, from bolt-actions to AR-15s chambered in 6.8 SPC. If you’re looking for availability, 6.8 SPC is it.

Hunting

Readers who are feeling a little down about the 6.8 SPC can rejoice in the hunting section. Sure, on paper, the .277 Fury can outperform the 6.8 SPC at the hunting club. However, there are two great advantages to hunting with the 6.8 SPC.

First, ammunition. Sig is the only company producing ammunition for the .277 Fury (at the time of writing), and this includes hunting ammo. The 6.8 SPC, on the other hand, is available from many manufacturers like Hornady and Winchester.

Shop 277 SIG Fury Ammo

Second, you don’t need a proprietary rifle to hunt with 6.8 SPC ammo. You can easily convert your AR-15 to fire 6.8 SPC with a simple barrel, bolt, and magazine change. (There are no factory bolt-action rifles chambered in 6.8 SPC at the time of writing.)

The caveat with 6.8 SPC is that it isn’t a great elk or big game hunting cartridge. It’s better for harvesting deer and smaller critters. Your effective range with the 6.8 SPC is going to be a maximum of 250 to 300 yards.

Overall, the 6.8 SPC is the better hunting option because it’s more available and has a great range. But if you want to take a trophy buck at 500 yards, then the .277 Sig Fury is the better choice.

Self-Defense/Home Defense

Both of these cartridges were designed with CQB in mind. Both have high muzzle energy, and can certainly stop any threat in your home.

However, if I had to choose one for home defense, it’d be the 6.8 SPC. Despite all of the advantages of the .277 Fury, a few fundamental aspects of the 6.8 SPC give it some advantages here.

The first advantage is how much ammo you can stockpile. Unfortunately, .277 Fury ammo isn’t as widely available as 6.8 SPC. Naturally, I’m going with the one I can get ammunition for.

The second advantage is penetration. With so much power behind it, the .277 Fury will easily blow through your interior walls and potentially strike your loved ones or neighbors next door.

The 6.8 SPC is capable of over-penetration as well – but it's definitely less likely to exhibit that problem than the .277 Fury. Since the 6.8 SPC is designed to increase the stopping power of the 5.56 – and any standard AR-15 carbine can easily be converted to fire it – it’s clearly the better choice for home defense thanks to a higher ammo availability and lower chance of over-penetration.

Neither of these options is as readily available as similar long-range civilian cartridges like the 6.5 Grendel or 6.5 Creedmoor. If you’re new to rifles and looking for something with great range and ballistics, it might be better to read up on more readily available types of ammunition.

Shop 6.8 SPC Ammo

Reloading

It’s important to consider what you can and can’t reload before upgrading to a new cartridge.

If your main focus right now is obtaining something you know is reloadable, it’s better to stick with the 6.8 SPC. This cartridge has been around for quite a while, so everything from dies to component bullets is pretty easy to find. Reloading data is readily available as well.

Sig has indicated that the hybrid case is reloadable. At the time of writing, we don’t know how long it will be before the company releases any load data for it. Unless you want to wait it out, the 6.8 SPC is better for reloading.

Ballistics

Remington and Sig both developed cartridges which improve upon the lethality of the military’s traditional 5.56 NATO. For a comprehensive breakdown of 6.8 SPC ballistics across various manufacturers and loads, check out our dedicated ballistics resource. The following charts will show you how they perform ballistically.

6.8 SPC Development and History

Back in 2004, Remington Arms teamed up with U.S. Special Operations Command and the U.S. Army Marksmanship Unit to design a new cartridge for the M4 carbine. The trio wanted to create a cartridge with better terminal ballistics in CQB, and do so while keeping the M4 in addition to modifying its existing components to work better.

Master Sgt. Steve Holland and Chris Murray took the lead on the project. They modified a 30 Remington case to fit in the chamber of the M4. This allowed for heavier projectiles and more pressure, so it seemed like a great idea at the time – especially because it had excellent energy transfer out of shorter barrels.

Unfortunately, Remington botched the chamber designs on the original 6.8 SPC, which created the potential for rounds to exceed chamber pressure specs. Remington took it back to the workbench and underloaded the ammo instead of fixing the chamber. Not unsurprisingly, the military declined to adopt Remington's do-over.

But Remington didn’t give up on the civilian market. They tweaked minor things, like adding 0.50” of free bore to the chamber and reducing the twist rate. It was too late for the 6.8 SPC to become a military cartridge by that point, but it performed well and has satisfied many American civilians' needs.

.277 Fury Hybrid Development and History

When the U.S. military asked the private sector to come up with a .277 caliber cartridge, Sig answered the call. Unlike Remington, however, Sig didn’t reuse outdated casings and match the cartridge to the M4.

Shop 277 SIG Fury Ammo

Sig instead developed a new rifle, and also designed a revolutionary case for what would become its 6.8x51mm cartridge. Sig’s new weapons system consists of the XM5 (now XM7) and its belt-fed LMG counterpart, the XM250. Coupled with .277 Fury ammunition, these rifles were unveiled in 2019 as the winners of the Next Generation Squad Weapon (NGSW) program for the United States military.

Although we don’t have a lot of details just yet regarding exactly how this short-action rifle with magnum power came to be, we do know that the military was asking for a very specific weapon, and Sig was able to deliver it.

The military needed something that can pierce level 4 modern body armor at longer ranges than the 5.56 NATO, and word has it that the .277 Fury can do it. Furthermore, it has a lot of energy for CQB to ensure effective hits and fast knock-down.

Some critics of the heavier cartridge have raised concerns about carry weight. They also point out that its case design has never been tried and tested in the desert or frozen tundra, so we can’t be certain we won’t see malfunctions in the coming years.

Nevertheless, it seems like a solid solution so far, and we’re excited to see how it performs.

Parting Shots

It’s been quite a few decades since a new weapon system hit the scene. The U.S. military has been using 5.56 NATO since Vietnam, however, so the fact that the Army is testing new weaponry isn’t too surprising.

It’s likely that we haven’t seen the last of 5.56 NATO on battlefields, but adopting a new, more versatile, and higher-pressure rifle cartridge with better armor-piercing capabilities seems to be the militart's end goal.

Whether you’re in the military, interested in military arms, or a civilian looking for some new cartridges, the .277 Fury and 6.8 SPC have a whole lot to offer. Whichever one you choose, you won't be disappointed!

Written by

Cassandra McBride