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Posted: 8/28/2013 2:22:10 PM EST
I'm building another upper as I sold my standard dpms 16" upper last week I'm trying to make a decision on barrel length. I want to try to make this upper as quite as possible without a can so what I want to know is how much difference barrel length makes on the noise level I'm not going to put a brake on it cause they tend to raise noise levels a lot so I'm thinking a 24" bull barrel I think this will be the quietest possible configuration any opinions would be great thank you Sean
Link Posted: 8/28/2013 2:50:54 PM EST
The purpose of the AR needs to be factored in too.


Are you using it to hunt with? Is it a target rifle, home defense or range toy?

Link Posted: 8/28/2013 2:58:39 PM EST
It's going to be for 2 to 300 yd varmint shots bought a17 wsm for it but got sick of waiting for ammo so now my gunshop bought it back and I'm going ar varmint instead noise is the big factor.
Link Posted: 8/28/2013 3:04:09 PM EST
If you can lug around a 24", go for it.

Mine was way too long and nose heavy to be carried very often.
Link Posted: 8/28/2013 3:04:16 PM EST
The shorter the barrel, the louder the report, at least it seems that way to me.

Below is a link to varmenter pic thread, if you look around in it you might find some good info on that type of AR.

Honestly, I don't know much about them.

http://www.ar15.com/forums/t_3_118/409091_.html
Link Posted: 8/28/2013 3:06:52 PM EST
In theory as well as in my experience, longer barrels tend to be quieter than shorter barrels.

When I am shooting my 24" Krieger barreled AR (no muzzle device), it is significantly quieter than my carbines (with flash hiders).

That is from the perspective of the shooter; I have no idea if there is much, if any, difference down range.

That 24" bull barreled AR is one heavy SOB, though. It also makes it easy to shoot 3/4 MOA groups.

Joe
Link Posted: 8/28/2013 3:08:26 PM EST
It is a high powered rifle round. Nothing short of a suppresor is going to make much difference in noise levels. It will still be ear splitting no matter the barrel length.
Link Posted: 8/28/2013 3:14:01 PM EST
I forgot to include this gun will not be carried only shot off my back deck just like it quiet to not irritate the family. The person that said his 24 is considerably quieter than his carbines is exactly the answer I'm looking for.
Link Posted: 8/28/2013 6:39:45 PM EST
Barrel Length Studies in 5.56 NATO Weapons; this has some good information.
http://sadefensejournal.com/wp/?p=1093
Link Posted: 8/28/2013 7:34:56 PM EST
Anything that can reach out and hit varmints at 300 yards is going to be pretty loud.

A few extra inches in barrel length won't make much of a difference in noise. I would base the choice on other things.

It sounds like a 20" barrel might suit you well anyways, though.

There are also some other options if you're interested in a bolt gun.

At 200 to maybe 225 yards you could get away with something like a .22 hornet. Certainly not a good choice for 300 yards though.

.17 HMR can push 200 yards, if it's not too windy. A little cross wind blows those tiny pills a mile of course at 200 yards.

Or use a subsonic .22 and sneak up on 'em.


Link Posted: 8/28/2013 11:25:00 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By donovansn585:
I forgot to include this gun will not be carried only shot off my back deck just like it quiet to not irritate the family. The person that said his 24 is considerably quieter than his carbines is exactly the answer I'm looking for.
View Quote

5 people tell you it won't be a whole lot quieter. 1 guy says it will.
Just keep asking until you get one person to give you the answer you want then.

Seriously though, a shorter barrel is a little louder TO THE SHOOTER because you are closer to the hot gases that exit the muzzle.
All AR15's fire the same ammunition, so they are all pretty loud.

Buy a suppressor if you are concerned with it being too loud.
Link Posted: 8/28/2013 11:37:03 PM EST
[Last Edit: 8/28/2013 11:39:16 PM EST by dangerdan]
Get a Noveski Kx3. It throws most of the blast forwards. Should be a little quieter to you.
Link Posted: 8/28/2013 11:58:05 PM EST
A lot of noise comes out the gas ports on the bolt carrier. To the shooter, you probably won't be able to hear a difference. Really, just get a suppressor. You'll be quieter, and you'll have a rifle that you can actually carry around.
Link Posted: 8/29/2013 12:51:43 AM EST
Unfortunately I live in a state where, because of the fish and game dept. they won't allow silencers because apparently too many people would be jacking deer in the dark boo.
Link Posted: 8/29/2013 6:05:49 AM EST
20" rifle is the smoothest shooter
Link Posted: 8/29/2013 6:07:07 AM EST
try a 20 " pencil barrel..add a DPMS 5.5 flash hider .. works pretty good.
Link Posted: 8/29/2013 6:23:47 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By hun001:
try a 20 " pencil barrel..add a DPMS 5.5 flash hider .. works pretty good.
View Quote


Hes varmit shooting.. no pencil needed lol.

Um, I'd say the length of the barrel.. doesnt do a whole heck of alot in terms of noise, but the difference from a 16" barrel to a 24" barrel for a shooter is the muzzle blast is 8 inches farther out.. hence it being quieter, but stand at a 90 degree angle to any .223/5.56 with a target crown/ A2 bird cage and the guns pretty much going to sound the same, I noticed no difference between the M16 or the M4.
Link Posted: 9/2/2013 5:32:04 PM EST
AFAIK some of the noise is related to how completely the power has burned when the bullet exits the muzzle.
My take is most rounds have fairly complete burns by 20 inches.
If you roll your own and use a slow powder 24 inch may be better.
There are some rounds that have been optimized for short barrels, but I have no idea if they would be an improvement.
Link Posted: 9/3/2013 4:24:36 AM EST
Decibel levels at the muzzle is also a function of bore pressure as the bullet uncorks, and as the shorter the barrel gets the pressure goes up; and as it increases so does the sound levels.

20" - 5,717 psi
14.5" - 8,150 psi
10.5" - 11,500 psi
7" - 17,040 psi

Source: http://sadefensejournal.com/wp/?p=1093
Link Posted: 9/3/2013 7:51:12 AM EST
[Last Edit: 9/3/2013 8:20:08 AM EST by JeffinVAB]
Originally Posted By donovansn585:
I'm building another upper as I sold my standard dpms 16" upper last week I'm trying to make a decision on barrel length. I want to try to make this upper as quite as possible without a can so what I want to know is how much difference barrel length makes on the noise level I'm not going to put a brake on it cause they tend to raise noise levels a lot so I'm thinking a 24" bull barrel I think this will be the quietest possible configuration any opinions would be great thank you Sean
View Quote

I regularly shoot my 24" barrel precision AR and ocassionally shoot my 11.5" barrel AR.

From the persective of people beside or directly behind you, the 24" barrel is much quieter and more tolerable, although still loud. The short barrel has a much bigger flash and concussion.

For deck shooting, build a small shooting portal out of sound/fiber board and lined with eggcrate/sound dampening foam. It makes a huge reduction in sound. It's possible to build one that is as effective as a supressor, but not practical to shoot through.

You could also consider using a sonotube of the diameter of your choice and lining it with with the thick (4" thick) sound dampening foam, but it's a little difficult to rig up unless you are shooting at a fixed target.
Link Posted: 9/3/2013 7:53:23 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By AR-4C:
Decibel levels at the muzzle is also a function of bore pressure as the bullet uncorks, and as the shorter the barrel gets the pressure goes up; and as it increases so does the sound levels.

20" - 5,717 psi
14.5" - 8,150 psi
10.5" - 11,500 psi
7" - 17,040 psi

Source: http://sadefensejournal.com/wp/?p=1093
View Quote

This.

Shooting my 7.5" pistol is ear splitting to be anywhere around it. When I am spotting for a friend with a 16" I'll stand directly behind him without ear protection (don't do this at home kids ). With my 20" standing beside it doesn't bother me. I would imagine with a 24" it will be all that much more quiet.

You will NOT get it down to a .22 level or a suppressed .223 but for somebody in. a house behind you with the doors closed I think it would be ok.

Just my opinion.
Link Posted: 9/3/2013 8:49:39 AM EST
Gunna be loud regardless of barrel length without a suppressor.

Longer barrel may seem quiter, but it will be a mute point considering any highpowered gunshot without a suppressor is loud.

suppressor is the only way to quiet it down
Link Posted: 9/3/2013 9:51:00 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By rifleman207:
It is a high powered rifle round. Nothing short of a suppresor is going to make much difference in noise levels. It will still be ear splitting no matter the barrel length.
View Quote


Yep, your going to be using hearing protection either way.
Link Posted: 9/3/2013 3:10:38 PM EST
Great ideas guys, going to build a shooting chamber
Link Posted: 9/4/2013 3:23:47 PM EST
All I know is that shooting my 10.5" AR seems alot louder than shooting my 22" bolt gun.
Link Posted: 9/5/2013 10:39:17 AM EST
Just read this from another thread if it helps.

"Non-suppressed sound pressure level increases exponentially with decreasing barrel length."

http://www.dtic.mil/ndia/2010armament/WednesdayCumberlandPhilipDater.pdf
Link Posted: 9/6/2013 7:07:47 PM EST
I have a 20" rifle (A4 clone) and a 20" upper. I shoot both without earpro from time to time as it is not needed.

I also have a Recce clone and the wife unit has an M4, and we use earpro religiously with those as it is necessary.




With the 20" AR15, the noise is just above that of a .22
Link Posted: 9/6/2013 7:20:54 PM EST
YEah, I think a 20" barrel is all you need, AND a LEVANG compensator (or KX3) will throw AS much of the sound forward as it can.
Link Posted: 9/8/2013 4:47:41 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Usagi:
I have a 20" rifle (A4 clone) and a 20" upper. I shoot both without earpro from time to time as it is not needed.

I also have a Recce clone and the wife unit has an M4, and we use earpro religiously with those as it is necessary.




With the 20" AR15, the noise is just above that of a .22
View Quote


This I don't get. I shoot 11.5" to 20." I hardly notice the difference between 16" and a 20" and there is no way I would consider no ear pro with the 20."
Link Posted: 9/8/2013 9:34:54 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By FargoZ71:


Hes varmit shooting.. no pencil needed lol.

Um, I'd say the length of the barrel.. doesnt do a whole heck of alot in terms of noise, but the difference from a 16" barrel to a 24" barrel for a shooter is the muzzle blast is 8 inches farther out.. hence it being quieter, but stand at a 90 degree angle to any .223/5.56 with a target crown/ A2 bird cage and the guns pretty much going to sound the same, I noticed no difference between the M16 or the M4.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By FargoZ71:
Originally Posted By hun001:
try a 20 " pencil barrel..add a DPMS 5.5 flash hider .. works pretty good.


Hes varmit shooting.. no pencil needed lol.

Um, I'd say the length of the barrel.. doesnt do a whole heck of alot in terms of noise, but the difference from a 16" barrel to a 24" barrel for a shooter is the muzzle blast is 8 inches farther out.. hence it being quieter, but stand at a 90 degree angle to any .223/5.56 with a target crown/ A2 bird cage and the guns pretty much going to sound the same, I noticed no difference between the M16 or the M4.



pencil is just as accurate.
Link Posted: 9/8/2013 9:44:39 AM EST

I think shorter barreled rifles are louder.

I was shooting beside a guy recently that had a 20" AR with a A2 FH.

He them brought out what appeared to be a 14.5" with A2X FH.

The shorty was louder from my perspective at the bench next to him.

Just my observation.



Link Posted: 9/8/2013 8:16:29 PM EST
[Last Edit: 9/8/2013 8:25:18 PM EST by DBR]
A longer barrel will have less actual pressure related muzzle blast than a shorter barrel. IME once you get to around 24" with 223 the practical barrel length effects are pretty well maxed out.

If you are mostly concerned about the sound signature behind the shooter the KX3 works. It is heavy and IMO ugly. I used one for a while. The Troy Claymore also works and is less heavy and ugly. In my tests they both change POI significantly and may affect group size. I did not test either for group size.

A significant component of the sound signature is the supersonic "crack" of the ammo being fired. It is an important part of the shot report that people hear and it is mostly down range. It has little to do with barrel length and a suppressor doesn't help.
Link Posted: 9/8/2013 11:59:42 PM EST
Barrel length is going to effect velocity more than sound issues. A 20" barrel is pretty much optimum for most shooting situations. I avoid bull barrels because I hunt with both my ARs. I just get tired of the weight. The lightest varmint gun I own is a Savage BMag 17WSM. It weighs 6 pounds less scope. My ARs hover around 8 to 9 pounds depending on their configuration.
Link Posted: 9/9/2013 5:35:42 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By PFC:
AFAIK some of the noise is related to how completely the power has burned when the bullet exits the muzzle.
My take is most rounds have fairly complete burns by 20 inches.
If you roll your own and use a slow powder 24 inch may be better.
There are some rounds that have been optimized for short barrels, but I have no idea if they would be an improvement.
View Quote


That's pretty much how I understand it. I'd also go without a muzzle brake or compensator since rate of fire will be lower and flash hiding isn't an issue with varmints.
Link Posted: 9/9/2013 5:37:21 AM EST
Link Posted: 9/9/2013 9:06:20 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By rifleman207:
It is a high powered rifle round. Nothing short of a suppresor is going to make much difference in noise levels. It will still be ear splitting no matter the barrel length.
View Quote


This!
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