[Highpower]

Originally Posted by kenhesr

At 200 yds with a 40x scope you can watch the 5.56 rd hit the target.

Say what? 40x???

[Sampleman]

First, the bullet does make noise. There is a sonic wave on any supersonic bullet which creates the crack. This is why weapons truly intended to be silent are down loaded to subsonic bullets. On a .22 rifle, this can be the majority of the sound heard at a distance. Should muzzle brakes effect this in any way? I can't think of how.

Second, the way that gas exands directly relates to how much noise is created. Without a muzzle brake, the predominent gas expansion is forward forming a cone. The gas molecules travelling at 2500 feet per second don't instantly complete a 90 degree turn. This in turn projects most of the noise forward. Anyone who has strayed past the plane of a muzzle knows this. It gets much louder. A muzzle brake completely changes this dynamic, refocusing the gas and thus sound perpendicularly by way of physical restriction. This absolutely changes the sound level of the firearm to those around and behind it.

Believe what you want, but if you set up on a bench next to a .300 Mag with a muzzle brake, secure all of your loose ammo and double muff.

[kenhesr]

Originally Posted by Highpower

Say what? 40x???

AHHH, thats just my shorthand for a fixed power scope, non-variable. 40x means 40 power magnification in the group I shoot with. I probably should have taken the time to type in the front objective ie; 40x52mm like the March 40xED scope, 40x45mm with the Leupold LEU53436 or 36x44mm Tasco World Class.

I should also explain that I was referring to shooting from bags & a rest. I'm not that good a shot!

The purpose of my reply was more about the brake in the picture than the scope. That brake is on a standard E.R. Shaw 24" barreled AR-15. With a 40 or even a 36 power scope, from a rest at 200 yds you can read the print on a beer can. With LC77 FMJ 5.56 surplus ball when you fire the rd, the view in the scope stays the same, you can watch the bullet hit the can thru the scope. Like shooting a .22lr at 50 yds with a 3x9x40mm scope. Kinda fun!!

I also have an AR set up with a 24" E.R. Shaw varmint Bull bbl but no brake, just a target crown. With a 40 power scope at 200 yds, forget it. You will hit where you aimed but the rifle moves enough from recoil, even on bags, you can't see the impact thru the scope.

I've been messing with weapons for so darn long I just Assume everybody knows what I mean. Wasn't trying to confuse ya, Ken

[Highpower]

Originally Posted by kenhesr

With a 40 or even a 36 power scope, from a rest at 200 yds you can read the print on a beer can.

I'll have to remember that next time I need to read a newspaper from 2 football fields away!

[kenhesr]

LOL!! I don't think I can read too much of the fine print, but you sure can pick which part of the BUDWEISER you want to hit.

Although they claim you can see a 6mm hole in a 600 yd target with the March 40xED scope, but for $2100.00 I think I'll stick with my 200 yd beer can killers. Take care, Ken

[mrm14]

"Believe what you want, but if you set up on a bench next to a .300 Mag with a muzzle brake, secure all of your loose ammo and double muff."

You mean one like this?

[Johnny45]

Yeah...I thought it was pretty much taken for granted that a true muzzle brake increases the actual decibels directed back towards the shooters ear, and even more so to the folks standing next to them. I don't think that really counts as a "myth". It's just fact.
Now, me, I'll hazard this...a muzzle brake, in order to be a real muzzle brake, must direct energy REARWARD in order to counteract the recoil of the cartridge. The bullet causes the actual recoil...all pressure is equal inside the chamber, and the bullet and bolt "shove" each other away from them, which pushes the whole gun back into your arm. The MUZZLE BRAKE is designed to catch some of the gas, and direct it rearward, to provide JET THRUST of a sort in the opposite direction of the recoil. Familiar at all with the principle of the "recoiless-rifle" (the large-caliber, military weapon)? A muzzle brake replicates on a smaller, and far less effective scale the equalizing effect of a blast in the opposite vector to the recoil of the bullet accelerating out the barrel.
Since the entire rifle is such a big, heavy chunk of metal and wood (or plastic, if that's your "thing"), it takes the impulse far slower than tiny little bullet. That means, given an equal force, it takes far longer to accelerate than the bullet does. The cartridge goes off...the bullet accelerates up the barrel, and the gun almost imperceptibly begins to move rearward, building speed as the bullet nears the muzzle.
As the bullet reaches the muzzle-brake ports, the high pressure gas is directed to the REAR, providing a very quick thrust or impulse to the rear, taking a lot of "oomph" out if the building acceleration of the gun/stock.

In conclusion, not only does a true muzzle brake truly direct blast (and sound) to the rear (not 90deg from the muzzle), but I doubt even a plain-muzzled rifle actually vents to a true 90deg. Ever seen muzzle-flash from a gun without a flash suppressor? (i.e. not the movie-gooks shooting back with their AK's)? It tends to spear out the front, with a relatively small blast around the muzzle itself. I suspect that flash suppressors do actually increase the heard-noise level to a small extent, since they DO direct some of the gasses outward...but they generally also provide a small area for the gasses to expand slightly before exiting the ports...and the lower the pressure, the slower(quieter) the escaping gas will be.
Of course, sound waves travel slightly different from the blast (that's why they still sound loud when you shoot plain-muzzled guns), but the vector of the blast makes a difference.
Listen to a loud (or even quiet, if you listen close) jet fly past at low level...as it comes it, it sounds relatively quiet (and this is ignoring the Doppler change in the pitch). It gets a bit louder as it gets about 15-20deg overhead, but when it passes 90deg...hooly shyte!!! Now imagine a jet with a muzzle brake directing that force forward?
LOL, in fact, that reminds me of the Harrier attack fighter(whatever version you want...GR.1 through AV-8B+) is notoriously loud to those on the ground, particularly when hovering or in V/STOL mode. Any guesses why? Because the jets are facing DOWN, toward the ground. It's even very loud in horizontal flight, due to the relatively small nozzle area to mass-flow...i.e. high speed exhausts, the same reason that older turbojets are so god-awful loud (of course, the Harrier is a turboFAN...turbojets are inherently loud, but the Pegasus turbofan in the Harrier is only loud because of it's nozzle configuration.

[mobius]

Think of this for a simple example. When you blow out you make a certain amount of noise, not much. Blow the same volume of air across a sharp edge and your noise level increases. That is not to say a muzzle brake will necessarily increase the volume of sound, though it easily could and probably will.

Fred
Molon Labe

[lonyaeger]

A conspicuous absence of Tango in this thread......?

[mrm14]

What I think is that the shooters either side of my brake are getting more percussion than the actual sound. Not to say that the report they hear doesn't seem louder because it does from what they would be otherwise hearing from their position with an unbraked rifle. That percussion is pretty hard on the ear drum even with muffs on. I think it's the percussion wave that gives a braked rifle it's "Bark". When I'm shooting my braked rifle I can't tell the difference in precieved decibles between the brake being on or off the rifle. Also, don't feel much if any of the percussion. Probably because I'm behind the damn thing.