.277 SIG Fury

01 / At a glance

The basics

Origin

United States

Introduced

2019

Ignition

Centerfire

Case form

Rimless, bottleneck, hybrid

Diameter

7.1 mm

Case length

51.2 mm

Rounded values to help you identify the cartridge, not manufacturing drawings. See the cited standard for exact dimensions and tolerances.

A short history

SIG Sauer designed the cartridge in 2019 for the Army's Next Generation Squad Weapon program, which aimed to replace the 5.56 NATO M4 carbine and the M249 squad automatic weapon. SIG announced a commercial version in late 2019, and the cartridge was accepted by SAAMI in 2020, with a drawing dated September 2020. In April 2022 the Army selected SIG Sauer's entries for the program: the XM5 rifle (later the M7) and the XM250 automatic rifle (later the M250), both chambered for the cartridge under the military name 6.8 common cartridge.

The commercial name .277 Fury and the military name 6.8x51mm describe the same family. The military load is the XM1186 general-purpose cartridge. SIG sells the cartridge to civilians, with the SIG CROSS bolt-action rifle announced in late 2019 and the MCX Spear semi-automatic rifle as the best-known firearms.

The design solves a specific problem. Rifle makers wanted a faster, flatter, harder-hitting bullet than 5.56 or 7.62 NATO, in a rifle not much larger than a standard one. The answer was a very high chamber pressure, which a conventional brass case cannot hold at that level. SIG's case therefore joins a steel head to a brass body with an aluminum locking washer.

A practical point for owners: the cartridge was built to survive military handling, and its pressure is the highest of any common rifle round. That is why the SAAMI drawing carries a note that pressure above 65,000 psi calls for a different case and firearm design. If you buy a rifle for it, treat the rifle and ammunition as one system, keep the ammunition in its original box, and do not mix it with other .277 inch ammunition.

It also helps to remember what the cartridge is not. It is not a replacement for a good deer rifle that you already own, and it is not a long-range match cartridge, since its bullet has a modest ballistic coefficient. It is a fast, flat-shooting, high-pressure cartridge for people who want exactly that.

Why people are interested

The first reason is the military adoption. A cartridge chosen to replace the 5.56 in a major army draws attention from shooters, and the MCX Spear and the CROSS put it in civilian hands.

The second reason is the speed. A 150 grain AccuBond load leaves a 24 inch barrel at about 3,120 ft/s, and a 16 inch barrel at about 3,240 ft/s in SIG data, with 2,830 foot-pounds at the muzzle. For a .277 inch bullet of that weight, that is a very fast load and the reason the cartridge attracts hunters.

The third reason is the novelty. A hybrid case is unusual, and shooters like to see how it works. The cost of that novelty is a narrow choice of ammunition, rifles and reloading components.

Specifications at a glance

Values are rounded for reference. Pressure and dimensions are from the SAAMI cartridge drawing, which also states that a pressure above 65,000 psi requires a different case and firearm design. Velocities are SIG Sauer figures.

Strengths and limits

The .277 Fury is a very high-pressure cartridge. These are the trade-offs to understand.

Honest advice: for most hunters and target shooters, the .308 Winchester, the 6.5 Creedmoor or the 6.5 PRC do the same work with cheaper, more available ammunition and many more rifles. The .277 Fury makes sense if you want the cartridge itself, or the rifles chambered for it.

Bullet and ammunition choice

SIG Sauer offers several loads, including a 113 grain hybrid ball, a 135 grain brass elite load, a 155 grain match load and a 150 grain AccuBond hunting load. Some of its earlier loads, including a 135 grain hybrid match and a 140 grain hunting load, have been listed as discontinued.

Note that some SIG ammunition is loaded in the hybrid case and some in a brass case. Check the box, because hybrid cases need the matching rifle.

Ballistics

The table and charts below show one factory load, a SIG Sauer 150 grain AccuBond hybrid load at 3,120 ft/s from a 24 inch barrel, with the rifle zeroed at 200 yards.

Reading the numbers

With a 200 yard zero the bullet rises about 1 inch above the line of sight at 100 yards, returns to the line at 200 and falls about 6 inches at 300, 17 at 400 and 35 at 500. A 10 mph crosswind moves it about 5 inches at 300 yards, 10 at 400 and 16 at 500. Velocity drops from 3,120 ft/s at the muzzle to about 2,210 ft/s at 500 yards, and energy from about 3,240 to about 1,620 foot-pounds.

The trajectory is flat for a rifle cartridge of this size, and the bullet keeps real energy at 500 yards. The wind drift is similar to a 6.5 Creedmoor, since the ballistic coefficient is modest. Use a bullet that expands at the speeds you expect, and check local rules for caliber and energy minimums.

Recoil and shooter comfort

Recoil is moderate to firm. The high velocity of the bullet gives the cartridge more recoil than a 6.5 Creedmoor in the same rifle weight, though less than a .300 Winchester Magnum. A suppressor and a muzzle device are common on rifles built for it.

Use good hearing protection, and consider both plugs and muffs on the range. The high pressure also means a loud report, so protect your hearing.

How to choose ammunition

SIG Sauer makes most of the commercial ammunition. Match the bullet to the job and test the load in your own rifle.

For hunting, choose a bonded or controlled-expansion bullet suited to the speed. For practice, ball and match loads cost less. Try more than one load, since a rifle often prefers one.

Check the headstamp and the rifle

Do not confuse .277 Fury ammunition with other .277 inch cartridges such as the 6.8 SPC. They are not interchangeable and the pressure of the Fury is much higher. Always read the barrel marking and the headstamp.

Cost

The hybrid case costs more than brass, and so does the ammunition. Plan your practice with that in mind.

How to choose a rifle

The right rifle depends on how you hunt or shoot. These are the points that matter most.

• Chambering and pressure. Buy only a rifle made for the .277 Fury. Its 80,000 psi is far above what a rifle for a brass-case cartridge is built for.
• Action. Semi-automatic and bolt-action rifles exist. The SIG MCX Spear is a semi-automatic and the SIG CROSS is a bolt-action.
• Barrel length. 16 inches gives a compact rifle with a loss of speed, and 24 inches gives more velocity.
• Twist rate. The cartridge uses 1 in 7 inches. Check the rate the maker uses.
• Weight. A lighter rifle is easier to carry and kicks harder. A heavier rifle is steadier.
• Suppressor. Check that the muzzle and the local rules allow one.
• Optic. A good variable-power scope with reliable adjustments suits the cartridge.

The SIG MCX Spear is the best-known semi-automatic, and SIG also made the CROSS bolt-action rifle. Check current catalogs, since the range is small and changing.

Zeroing and range practice

A 200 yard zero is a good starting point. With a 150 grain AccuBond the bullet stays within about 1.5 inches of the line of sight out to 150 yards and drops about 6 inches at 300 yards. That lets you hold on the vital area out to about 300 yards.

Zero at 100 yards on paper first, then confirm at 200. Shoot at 300, 400 and 500 to learn your own drops, and write them on a card. The numbers in this guide are estimates from a model, and your barrel, load and air density will move them. Wind is the main problem past 400 yards, so practice judging it.

Shoot from field positions as well as a bench. Practice at the distances you plan to take.

Practical uses

Deer and similar game

The 150 grain AccuBond load is made for deer-size game. It shoots flat and carries energy to 400 yards or more, though closer shots are better. Check local rules on minimum caliber and energy.

Hogs

It handles hogs well with a bonded bullet, and the semi-automatic rifles give quick follow-up shots.

Elk

It is a light choice for elk, and many hunters prefer a larger cartridge for the extra margin. Check your local rules.

Range and tactical use

The cartridge was designed for military use, and the MCX Spear is popular as a range rifle. Cost is the main limit on volume practice.

.277 Fury vs similar cartridges

The table compares the .277 Fury with the cartridges it is usually weighed against. Figures are rounded and use SAAMI pressures.

Against the .308 Winchester, the Fury has the same case length and much higher pressure, with a smaller bullet at higher speed. Against the 6.5 Creedmoor and 6.5 PRC, it offers more speed and less choice. Against the 6.8 SPC, it is a much larger and faster cartridge. The shared .277 inch diameter does not make them interchangeable.

Care and storage

Clean the bore after a day of shooting, and follow the barrel maker's advice. Inspect the action, the magazine and the scope mounts for tightness. Rifles for this cartridge see high pressure, so follow the maker's inspection schedule. Store the rifle unloaded and locked, with the ammunition separate and away from children.

Safety and common mistakes

• Never fire .277 Fury ammunition in a rifle not chambered for it, and never fire another cartridge in a .277 Fury rifle.
• Do not confuse it with the 6.8 SPC or other .277 inch cartridges. Read the barrel marking and the headstamp.
• Treat every rifle as loaded. Keep your finger off the trigger until the sights are on the target.
• Know your target and what lies beyond it. A rifle bullet can travel several miles.
• Wear eye and ear protection.
• Check the bore for obstructions before you load.
• If you reload, use only data and components made for the cartridge. This page does not contain loading data.
• Store firearms and ammunition locked and apart, away from children.

Sources

Sources reviewed · 29 October 2026

1. Wikipedia · .277 Fury ↗
2. SIG Sauer Elite .277 Fury 150 gr AccuBond Hybrid (retailer page) ↗