Tech. difference bet. muzzle break/flash hider

[Little-e]

What causes one to reduce muzzel flash while the other does not? On an M-16 the slots are cut horizontal (flash hider) and on my post ban AR there are slots cut vertical with a slight angle (muzzle break). What causes the difference?

 

[Cheapo]

The design intent and the overall effects make the difference, although many flash hiders have a limited muzzle brake effect.

To be a flash hider, it must break up the mass of powder gases enough to cool them below luminescence, and also prevent ignition of some flammable byproducts upon contact with atmospheric O2. This generally requires more ports and narrower exit passages than are needed for an effective muzzle brake.

I've heard that the ATF has some standard regarding how much the flash can be attenuated before a muzzle brake device is deemed to be a flash hider. Never bothered to look it up or remember reports of what this standard is.

Now here's a query--it's perfectly legal to put a flash hider on my revolver, right?

 

[Art Eatman]

A muzzle brake is specifically intended to reduce recoil. Any reduction in flash is mostly incidental to the designed purpose.

A flash hider in the "old days" was simply a cone-shaped attachment. You can see pictures of this style on older machine guns and some of the 20mm "anti-tank" guns of the past. It was intended to reduce the shoter's loss of night vision, primarily, rather than hide the flash from an enemy.

These Klintonista laws make things somewhat confusing, but any gun not banned on account of bayonet lugs and flash hiders and wrong colored paint or what-the-hell-ever can be shot with a flash-hider attached. If not, I've obviously missed something...

FWIW, Art