For all the wonders of ballistics in the heart of a rifle, gunmakers tend to give up at the muzzle. (Rob Curtis / Staff)
You can go cross-eyed reading the fine print specs of the modern rifle barrel advanced materials and coatings, rifling profiles and twist rates. But for all the wonders of ballistics in the heart of a rifle, gunmakers tend to give up at the muzzle.
If you want to maximize accuracy and reduce recoil, muzzle lift, flash and concussive force, then you must address the muzzle.
The state of your muzzle and the devices you add to it affect the venting of the superheated gases that drive the bullet down the barrel.
Properly "crowning" the muzzle for accuracy means machining the internal edge of the bore to uniformly release the gases. Uneven venting can impart "yaw" or off-axis spin to the bullet as it leaves the barrel.
Accuracy also takes a hit if your bullet catches or drags on something as it leaves the barrel. Most decent makers clean up their barrel ends. Full-on custom crowning is more of a boutique service for long-range rifles used for slow fire.
Most rifles tactical, in particular benefit from a brake. Also known as a compensator or "comp," a brake tames recoil. (Though some may argue the point passionately, the terms "brake" and "comp" have become practically interchangeable. Plenty of muzzle devices do both, so the distinction has been lost in practical terms).
Most brakes use baffles, ports or a combination of both. Baffles limit how much of the expanding gas can follow as the bullet passes through the muzzle, then vent the gas to the rear and sides to counteract recoil.
Ports are holes that redirect expanding muzzle gases to produce directed thrust.
The upsides: A brake makes your rifle more comfortable to shoot and allows you to keep your muzzle aimed at your target for multiple shots.
The downsides: Brakes direct significant sound and concussion to the sides, which can be distracting to anyone shooting nearby. Some brake designs can reduce muzzle flash but don't eliminate it. This isn't a big deal for hunters and plinkers, but shooters who want to conceal their positions will have to weigh speed and accuracy against signature reduction offered by flash hiders.
Rather than concentrating or redirecting muzzle gases for accuracy, flash hiders disperse those gases and any unburned gunpowder for stealth.
Muzzle flash occurs when superheated and fast-moving gases from the gunpowder explosion travel down the barrel and hit the low-pressure, oxygen-rich atmosphere past the muzzle. These gases contain trace amounts of burning and unburned powder that ignite and produce a flash as the gases and atmosphere collide. The hider disperses the gases, slowing and cooling them before friction and pressure cause them to burn. The most efficient hider designs use open tines to disperse the gases in a vortex as they leave the muzzle.
Muzzle flash at night can give away your location, interfere with your nighttime adapted vision and cause momentary whiteout (or greenout) of night-vision goggles.
To choose the right muzzle device for your rifle, consider:
Barrel length: A standard 16-inch rifle barrel in .223 caliber produces about 7,000 psi of pressure at the muzzle, while a 10-inch barrel can pile on twice that, which can take a toll on a flash hider. If you're going for a short barrel of less than 14.5 inches, look for a flash hider or brake made with material that can handle the abuse.
Suppressor compatibility: All suppressors' fast-attachment systems are proprietary. If you run a can, you'll be limited in your choice of muzzle devices. Those designed to work with suppressors usually have "adapter" in the name or description.
Durability: Almost all muzzle devices will outlive a barrel provided they can withstand the rigors of daily use. Thanks to advances in metallurgy, modern open-tine hiders are stronger than the original A1 design that broke and led to the Army's adoption of the stronger, enclosed A2 birdcage-style hider. In compensators, look for beefy connections between baffles that won't get crushed in a muzzle strike.
Possibility of bore obstruction: Getting vegetation stuck in the tines of an open flash hider may be a problem in dense jungle. It's pretty rare and only worth mentioning because it was a popular, but largely pointless, armchair warrior's argument against the open-tine design in the past.
Installation: Unless you're running a sound suppressor, flash hiders can be installed using a simple crush washer. Brakes and some sound suppressor adapters are installed using shims so that the ports and/or sound suppressor mounting index pins face the right direction.
Size and weight: I'm normally a stickler for weight, but these are only a few ounces, size dictated by caliber and peculiarities of the muzzle profile of the host weapon.
The length of a muzzle device can be added to get the overall barrel length of a short barrel to comply with the ATF's short-barrel regulations, as long as it's welded into place. A long muzzle device can bring a 14.5-inch barrel up to 16 inches and prevent the need for paperwork and a tax stamp.
Thread pitch and caliber: Muzzle devices come sized by caliber and thread pitch, and some rifles have nonstandard barrel ends and require a device with a specific length and inner profile. You'll have no trouble finding ½-inch/28 threads-per-inch devices for an AR/M16/M4, while ð-inch/24 threads is common on .308-caliber barrels. If your barrel isn't threaded, a gunsmith or machine shop likely can thread your barrel for less than $100.
Cost: An A2 birdcage-style flash hider can be had for less than $10, while a highly optimized brake can push $165. Plan on dropping $100 to $150 for a quality device.