Why is my AR-15 so loud?

[alfon99]

Ok, I just got an AR-15 in 5.56 with a 18" barrel, and to my surprise it is considerably louder than my VZ58 in the same caliber with a 11.75" barrel, using the same ammo. It sounds louder at a distance, and also up close. I thought it wasn't going to be that loud because of the barrel length. It has a flash hider, not muzzle brake. Any thoughts?

 

[bldsmith]

For the shooter the gases escaping from the blowback make it sound significantly louder. Also if your standing to the right of the shooter you can get a blast effect. Just my observations.

 

[alfon99]

For the shooter the gases escaping from the blowback make it sound significantly louder. Also if your standing to the right of the shooter you can get a blast effect. Just my observations.

Yes, but it is also louder at a distance.

 

[shadow9]

~2,850fps MV vs ~1,950. Also heavier bullet on the VZ so more time to burn up powder as it's going through the barrel.

As others have stated - may also be your flash hider. While it doesn't necessarily affect recoil, forcing the gas through those tighter slots could affect noise...although I've got NO Scientific or engineering standing to this assumption.

 

[Davek1977]

~2,850fps MV vs ~1,950. Also heavier bullet on the VZ so more time to burn up powder as it's going through the barrel.

Actually Alfon has stated it was louder WITH THE SAME AMMO.....His VV58 is in .223, not the 7.62x39 you are (assumingly) referring to in the above post.

 

[kimberkid]

How did you determine it was louder?

Did you use a decibel meter & compare or just an informal observation?

 

[Tirod]

An anecdotal observation isn't going to quantify exactly how much louder one gun is vs the other.

Shooting under a concrete canopy vs open air would make all the difference. Unless we are given every significant detail in exacting manner, there's no way other than guessing what you might be experiencing.

Same ear plugs, same range, same day, with the exact same lot ammunition, with decibel meters set up, and record the difference. Then we just might be able to say more, which all that data would anyway.

One difference is that the CSA vz58 may be using a different flash hider that throws more noise forward. The typical issue AR15 flash hider throws more gas up, to keep the barrel reaction minimized, and that causes sound waves to have another 90 degrees less travel to the ear.

When I built my AR15, I deliberately chose the Black River Tactical because it was shown in testing to be 3-5 decibels quieter than an issue flash hider at the shooter's ear.

Put it under a concrete canopy, and all bets are off. Like the difference between a saxophone and clarinet, how the flash hider is designed alters the sound.

 

[jerkface11]

Pretty much has to be the muzzle device.

 

[Destructo6]

So, how do you like that short Vz58? I'm jealous.

Anyway, I was thinking:

• although the ammo is the same, the barrel is shorter, therefore less velocity.
  as stated, the muzzle device is not the same and may direct blast differently

What muzzle device does the AR have?

 

[shadow9]

Actually Alfon has stated it was louder WITH THE SAME AMMO.....His VV58 is in .223, not the 7.62x39 you are (assumingly) referring to in the above post.

Oh, yeep. Missed that part apparently.

 

[Louca]

Had a shoot at our club a couple of weeks ago and there were LOTS of ARs being fired. All were shooting the same (XM193) ammo. The quietest rifle, hands down, was a target/varmint style gun with the usual (16-in) barrel length, but NO FLASH HIDER. Big difference.

Lou

 

[alfon99]

So, how do you like that short Vz58? I'm jealous.

Anyway, I was thinking:

• although the ammo is the same, the barrel is shorter, therefore less velocity.
  as stated, the muzzle device is not the same and may direct blast differently

What muzzle device does the AR have?

The AR-15 has a vortex flash hider, and the VZ has no muzzle device.

Could it be the flash hider? I know that muzzle brakes make a gun louder, but I never heard about a flash hider doing so.

Don't know if I mentioned it, but I was using Aguila .223 55gr FMJ ammo.

 

[Destructo6]

My guess is the lack of muzzle device on the Vz directs all blast downrange.

 

[Tirod]

Simple open muzzle allows the exhausting gas to blow mostly forward, which is where the largest part of the sound waves would travel. The Vortex is a four prong birdcage, the blast directed at 90 degrees to the muzzle, making the sound waves travel back to the ear much more easily.

Muzzle devices are used to direct gases and assist the shooter to be more accurate, or suffer the noise less. Every one of them makes a tradeoff between noise and some kind of recoil reduction, up and including suppressors.

 

[RussellC]

Last year I was at an outdoor range shooting my AR, 16" barrel, A-2 flash hider.
The guy next to me and his young son were shooting a large caliber bolt rifle.

After several shots the son walked over and asked what I was shooting, he couldnt believe how loud it was...

I assumed it was because of the 16" barrel, but I guess maybe not. I always hear AR pistol guys talking about how loud they are.

Russellc

 

[benEzra]

The AR-15 has a vortex flash hider, and the VZ has no muzzle device.

Could it be the flash hider? I know that muzzle brakes make a gun louder, but I never heard about a flash hider doing so.

I've never heard of a flash suppressor making a gun louder, either. My 16" AR has a Vortex and it seems (subjectively) to be no louder than a 16" AR with a bare muzzle, and certainly not as loud as a 14.5" (never mind an 11.5").

Simple open muzzle allows the exhausting gas to blow mostly forward, which is where the largest part of the sound waves would travel. The Vortex is a four prong birdcage, the blast directed at 90 degrees to the muzzle, making the sound waves travel back to the ear much more easily.

The Vortex doesn't redirect any gas to the sides that wouldn't already be going to the sides (it would seemingly reduce it, by blocking 50% of the area to the sides). The tines are longitudinal and flat on the inner radius, so if anything it redirects blast forward. There is a slight helix to the positioning of the tines, but not much.