277 Fury Ballistics

“We want a new rifle cartridge that is more effective at neutralizing enemy combatants,” said the United States Army. “Especially ones who are outfitted with modern body armor that our 5.56×45 ammunition has difficulty penetrating. Let’s start a Next Generation Squad Weapon program in 2017. That way multiple defense contractors can propose suitable replacements for our 5.56 M4 carbine and M249 SAW light machine gun!”

That’s more or less what the U.S. Army said. Here is (also more or less) how SIG Sauer responded:

“That sounds great, U.S. Army! Here – check out the XM7 and XM250 we have designed around a novel short-action rifle cartridge of our own design and creation: the 6.8x51mm Common Cartridge, which shall also be referred to as ‘277 SIG Fury!’ We think you will agree it is a massive upgrade over the 5.56. Why, it’s arguably even better than your 7.62x51mm (which is analogous to the commercial 308 Winchester cartridge).”

“Wow,” said the U.S. Army upon witnessing those firearms in action. “Just wow. We love what we’re seeing, SIG. Forget all those other defense contractors. We are adopting your creations!”

But How Does the 277 Fury Shoot?

To be certain, though it may supplant the 5.56, the 277 Fury can hardly be argued to be very similar. It shares a nearly identical length as the 7.62×51, and performs much more similarly to it.

To that end, the 277’s ballistic performance is indisputably better than the 7.62×51’s (and by extension the 308 Win’s). When loaded with bullets of the same weight and style, the 277 invariably exhibits the flatter trajectory, and also conserves higher striking energy at any point downrange. That’s a testament to its maximum loaded pressure of 80,000 psi compared to the 58,000-60,000 psi that 7.62×51 is typically loaded to.

At present, very few types of 277 Fury ammunition are available to the general public (which isn’t helped by the fact that SIG is the only major manufacturer producing it; Lake City Army Ammunition Plant has the potential to change that in a big way). Here are ballistic data for the three 277 cartridges currently listed for sale on SIG’s website.

277 Ballistics Table

Scroll right on the table to see velocity, energy and trajectory data.

How Is It Compared to Other Cartridges?

Looking at 277 data alone is illustrative, but doesn’t give you a sense of how much better or worse the new round’s performance is relative to that of other rifle cartridges.

In the interest of perspicacity, we have assembled a chart comparing multiple different cartridges’ ballistics. Note that we selected cartridges loaded with 150 grain AccuBond projectiles; or, barring that, the closest style of bullet we could get to the AccuBond. The exception is the 5.56 round, which represents the M855 performance the 277 is intended to supercede.

The data confirm what you may have already suspected:

1. The 277 does not compete with the magnum rifle cartridges that were developed for big game hunters. These dump way more energy into their bullets, and launch them across flatter, harder-hitting trajectories because of it.

2. The 277 does outclass the U.S. Army’s outdated 30-06 Springfield, as it does the 308. It beats out non-magnum hunting cartridges, and absolutely trumps intermediate combat cartridges like the 5.56 and 300 AAC Blackout.

The 277 is still fairly early on in its lifespan. Ammunition is difficult to find, and expensive. Appealing though its ballistic performance might be, the average Joe may have difficulty justifying an investment in the 277.

But as the U.S. Army increasingly utilizes the new cartridge – and more and more Americans become accustomed to its performance as a result – the 277 will quite likely encounter higher demand from the commercial market. When that starts happening, the 277’s ballistic performance is nearly certain to garner a large fanbase.