I was hanging out with a military friend of mine, Captain Morgan, and I started thinking about flash suppressors. Since the main feature of one is the open front vs closed front of muzzle brake, what if you put on a 7.62 or larger brake on the AR? It is still a brake but now it has a larger front opening.

Or am I missing any internal differences between the two?

So what's to keep you from mounting a brake made for 7.62x39 on a rifle chambered for 5.56 NATO?  Nothing I know of.  And as long as there's a BATF letter approving the brake you SHOULD be legal.

Arock

The BATF holds the view that any device that functions as a flash suppressor is a flash suppressor, regardless of its design and intended use.     It doesn't matter if it's a compensator, muzzle brake, or flash suppressor by name, but it does matter if it behaves as a flash suppressor.  

Open front or closed front (except for a hole for the bullet to pass through) doesn't matter to the ATF.  You simply choose the brake that performs in a way that you like.    Personally,
I'm not a fan of most brakes due to the significant increase in noise they create, particularly to the sides where your neighboring shooters are trying to shoot.

Incidentally, the BATF's position on silencers is essentially the same.  If it behaves as a silencer, it's a silencer, even if it's a potato stuck on the muzzle, though in that case the evidence with either rot or sprout roots before the trial date comes.

CJ

cmj...I think what JBear is getting at is the MAIN physical difference between an A2 birdcage flash suppressor and say a Wilson muzzle brake is the size of the front exit hole.  There doesn't appear to me to be a restriction on the size of the exit hole on a muzzle brake as long as its a legal brake.  With that in mind, what's to prevent using a 7.62mm or even a .458 SOCOM muzzle brake on a 5.56 NATO barrel?  If the muzzle brake is BATF approved (and at least designs two are) it looks like he should be able to use any brake on any barrel as long as it's still a brake.  What say?

Quoted: I was hanging out with a  friend of mine, Captain Morgan,

I used to hang around with him too before I quit drinking...

Oh wait, you aren't talking about alchohol...nevermind

This "brake" idea is kinda interesting... anybody tried it yet??

Quoted: This "brake" idea is kinda interesting... anybody tried it yet??

Yeah, I find that a mason's hammer works best.

do you use the hammering face or the chiseling face...