Suppressor question

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Thom
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Suppressor question

Post by Thom » Sun Jun 09, 2019 10:59 am

New to suppressors. Is it better to use s suppressor on a short barrel pistol(7.5 inch) or a 16 inch barrel? Which is quieter?

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Thom

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alamo5000
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Re: Suppressor question

Post by alamo5000 » Sun Jun 09, 2019 1:12 pm

Longer barrel for sure. If you are going for ultra quiet. That's the short answer.

Longer answer below... (for learning purposes)... when you pull the trigger the hammer drops and powder starts to burn. The pressure in the chamber is X PSI for a given round...that pressure is what drives the bullet from the case and down the barrel.

There is only so much chemical energy, ie pressure released from powder burning but in a longer barrel those hot gasses have more space to expand.

So when a bullet travels down a 7 inch barrel the pressure will be much higher upon bullet exit with all other things being equal vs a 12 inch barrel or a 16" barrel.

Here is an article on 5.56 that you can read, but pay attention to the chart titled "Bore Pressure at Exit"

http://www.sadefensejournal.com/wp/barr ... o-weapons/

Most modern suppressors are tuned to work safely within given pressures and will work optimally at certain barrel lengths, which in general is the 16 to 18 inch range if we are talking 5.56. Every caliber and combination will have a slightly different answer.

Note: There are several things that make noise in a firearm. The action if it's semi auto. That's at least 120+ DB at the ear even if you just cycle an empty chamber. Port pop also applies to semi autos. This means gas escapes out the chamber rather than the muzzle. A 5.56 SBR will meter around 145DB at the ear using regular ball ammo because of this alone.

The bullet flight itself makes noise. It creates turbulence in the air as it flies. Military Arms Channel and Huey Outdoors both metered the noise levels of bullets flying downrange and they are pretty loud. You can watch for yourself on their channels. Suppressors generally don't do anything about any of the above mentioned things.

What the suppressor does is control the hot gasses that are escaping from your bore and releases them in a controlled manner which tames down the loudest part, which is the immediate time when the bullet exits the bore and hot gasses get released. Again, when you take the lid off of something higher pressure vs lower pressure the immediate noise will be higher with corresponding pressure (PSI).

All other things being equal (ammo etc) a shorter barreled gun will be baseline much louder than a longer barrel gun. The suppressor will tame down that muzzle blast from the relative baseline of a given gun and ammo combination. If you have a gun that meters 170+ at the muzzle it will be louder than a gun that meters 160 at the muzzle even when you introduce a suppressor into the mix.

Higher PSI at bore exit = bigger boom at the muzzle.

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Re: Suppressor question

Post by alamo5000 » Sun Jun 09, 2019 1:46 pm

I will also add that people (especially here) like to play around with various hand loads that are optimized for different barrel lengths. I too really like this. IE faster powder in a shorter barrel can produce equivalent velocities consistently, but can also be quieter. Conversely I've shot some factory loaded subsonics that were loud as hell even with a suppressor. The powder of choice being the main difference.

It's all about producing and mitigating gas pressures primarily at your muzzle which will depend on your host weapon and a ton of other factors.

A bolt gun will always be quieter to the shooter because that port pop I mentioned above is virtually eliminated.

For supersonic rounds the sonic crack of the bullet alone, even if you had a totally silent rifle with zero muzzle blast would make noise around the 140 DB range depending of course on the bullet.

Basically you have many different aspects to look at this from. Do you want this quieter for the shooter or do you want the overall level of everything to be quiet?

If you shot tailor made subs out of a 16" bolt gun it technically might be quieter, but it probably won't be THAT much quieter than tailor made subs shooting out of a 9" barrel.

The minute you go into other angles of this though that changes variables. My response above was more about 'how suppressors work'...

The best thing is to just figure out what kind of gun you want to suppress and for what purpose and go from there. For example a 16" bolt gun shooting 220 grain bullets at 1000 fps might be quieter but it won't deliver any more energy to the target than a 9" gun.

1-2 DB is pretty much very hard to detect with the ear, but 4 or 5DB is definitely noticeable.

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Re: Suppressor question

Post by alamo5000 » Sun Jun 09, 2019 2:28 pm

alamo5000 wrote:
Sun Jun 09, 2019 1:46 pm
The best thing is to just figure out what kind of gun you want to suppress and for what purpose and go from there. For example a 16" bolt gun shooting 220 grain bullets at 1000 fps might be quieter but it won't deliver any more energy to the target than a 9" gun.

1-2 DB is pretty much very hard to detect with the ear, but 4 or 5DB is definitely noticeable.
On that note a 16" barrel shooting supers will have a substantial advantage for terminal performance shooting supersonics because, well you can get a lot more velocity out of a 16" barrel vs say a 9" barrel. Bullet performance on soft targets (IE pigs, deer) is substantially dependent on velocity. Generally speaking faster is better for most 308 bullets.

On a shorter barrel you can still get good performance but typically you will shoot lighter bullets at closer ranges because of velocity concerns.

All in all it depends on your purpose. Finding a good all around mix is the key, but the fundamentals are the same. AR platform or bolt action? Which one suits your needs?

Also noting the obvious very loud noise from shooting supersonics (you will still need ear pro even with a can) people that chase down a suppressor because someone online said it's 2 DB quieter in their test is not the best way to select a suppressor in my opinion.

How the cans you are looking at mount to the gun, to how big, fat, long, how much they weigh, etc all come into play. Don't go by just pure internet lore meter numbers because somebody's meter might be off, they might be using under power ammo, they might be using cheap loud ammo, they might live in a different environment than you do (mountains vs sea level) or a whole host of things that can impact meter readings.

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Re: Suppressor question

Post by alamo5000 » Wed Jun 19, 2019 11:12 am

As always I am constantly learning. Now I have to go back and question all of my assumptions that I made above.

https://www.youtube.com/watch?v=WDrPEdChCp0

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Re: Suppressor question

Post by golfindia » Wed Jun 19, 2019 12:15 pm

That's interesting. So many questions.

Were those A weighted measurements? I can't see the muzzle devices on those 3 rifles, but I assume they are all the same. Lastly, this should really be done more than once, in opposite barrel length order.....

The 10.5" barrel unsuppressed muzzle reading is 171db, while the 16" unsuppresed muzzle is 174. BUT.... The 10.5" unsuppressed at-ear is 157 and the unsuppressed at ear of the 16" is 153. So what are possible explanations that one could be louder than the other one at the muzzle but quieter than the other one at the ear? Or vice-versa?

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dellet
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Re: Suppressor question

Post by dellet » Wed Jun 19, 2019 11:51 pm

golfindia wrote:
Wed Jun 19, 2019 12:15 pm
That's interesting. So many questions.

Were those A weighted measurements? I can't see the muzzle devices on those 3 rifles, but I assume they are all the same. Lastly, this should really be done more than once, in opposite barrel length order.....

The 10.5" barrel unsuppressed muzzle reading is 171db, while the 16" unsuppresed muzzle is 174. BUT.... The 10.5" unsuppressed at-ear is 157 and the unsuppressed at ear of the 16" is 153. So what are possible explanations that one could be louder than the other one at the muzzle but quieter than the other one at the ear? Or vice-versa?
I think what happens is based on the timing of the bolt unlocking. If the ejection port opened at the exact same time as the bullet exits the barrel, the sound should be the same level. The longer the bolt stays closed, the less noise you have out the port.

I have actually seen similar results in velocity, where the only change made was the spring. Weaker spring, quicker opening of the bolt, less velocity. It really shows up with suppressed subs when you can chart velocity drops as you open the gas port.

What would need to be done is to actually chart bolt speed against DB numbers, along with time between bullet exit/muzzle reading and bolt open/port reading.

I would also be interested in a comparison of the two barrels at the muzzle with the gas system turned off.

I look forward to the explanations in the next video.
300 Blackout, not just for sub-sonics.

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Re: Suppressor question

Post by STINKEY » Sat Jun 22, 2019 12:44 pm

I got a can and have tried using 3 different platforms to base my conclusions.
Single shot
16" AR Rifle
7.5" AR Pistol

1st. They are an absolute blast and the biggest pain at the some time.
2nd. On a long barrel you will have problems with cycling. This results from a mid-range gas system. At the same time you have to decide on which bullet weight to use because of the bullet strike and drop are different in most weights.
3rd. Once you have gone thru the weight/powder drop combinations....... you have to keep that platform reserved exclusively to sub-sonic on the 16".
4th. On the 7.5" platform which used the required pistol length gas system I could not consolidate the sight picture between 50 and 100 yds. 3 MOA Red Dot and I get MOA at 100 yds (180 gr. Match) but need more range time to figure a point of aim for both 50 and 100 yds. :roll: :shock: without serious adjustment. :idea:
5th. Cycling problems arise if you take the can off because the increased back pressure is needed ........... I can say I have gone thru hundreds of combinations to reach these conclusions.

Sticking with the super sonic loads (110 gr Nostler) and just quieting the blast down a bit is where I'm at now.

This will be different if you don't reload and are satisfied with your current results using overpriced factory ammo.
Current plans include further testing but this is expensive and have to build up my stock again.

SIDENOTE----- Has anyone used TITE GROUP in the 300?????
If they say it can't be done.... I have or at least thought about it....... 8)

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dellet
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Re: Suppressor question

Post by dellet » Sun Jun 23, 2019 11:01 am

STINKEY wrote:
Sat Jun 22, 2019 12:44 pm
I got a can and have tried using 3 different platforms to base my conclusions.
Single shot
16" AR Rifle
7.5" AR Pistol

1st. They are an absolute blast and the biggest pain at the some time.only if you don’t understand the cartridge and/or the firearm
2nd. On a long barrel you will have problems with cycling. This results from a mid-range gas system. At the same time you have to decide on which bullet weight to use because of the bullet strike and drop are different in most weights.long barrels are no problem, subs in a 20” carbine gassed barrel will still be subs in any shorter barrel. If you have a mid-length gas system and are having problems, it’s because you chose poorly when you picked the barrel. Please see note above.
3rd. Once you have gone thru the weight/powder drop combinations....... you have to keep that platform reserved exclusively to sub-sonic on the 16".No you don’t, see above
4th. On the 7.5" platform which used the required pistol length gas system I could not consolidate the sight picture between 50 and 100 yds. 3 MOA Red Dot and I get MOA at 100 yds (180 gr. Match) but need more range time to figure a point of aim for both 50 and 100 yds. :roll: :shock: without serious adjustment. :idea: PLEASE see first note. A 3” drop between 50 and 100 yards will be hard to consolidate to a single sight picture. Since you have a 3 MOA dot, you can get close by using a 50 yard “0” at the top of the dot and your 100 yard at the bottom. Keep in mind your bullet will be dropping around 1” per 10 yards at that distance,so what you are wanting to do is not practical for any precision.
5th. Cycling problems arise if you take the can off because the increased back pressure is needed ........... I can say I have gone thru hundreds of combinations to reach these conclusions.this is completely dependent on powder choice, if you understand the how the firearm operates, understand gas pressure and volume with a reasonable handle on burn rates, the can is not needed. PLEASE SEE NOTE #1

Sticking with the super sonic loads (110 gr Nostler) and just quieting the blast down a bit is where I'm at now.

This will be different if you don't reload and are satisfied with your current results using overpriced factory ammo.
Current plans include further testing but this is expensive and have to build up my stock again.

SIDENOTE----- Has anyone used TITE GROUP in the 300?????yes
You have posted this same basic misinformation multiple times and it’s frustrating to see. If you would like some help, you might start a thread asking for it. The problems you are having are due to a complete misunderstanding of the fundamentals of the cartridge and/or the AR rifle.
300 Blackout, not just for sub-sonics.

alamo5000
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Re: Suppressor question

Post by alamo5000 » Sun Jun 23, 2019 12:54 pm

dellet wrote:
Sun Jun 23, 2019 11:01 am
You have posted this same basic misinformation multiple times and it’s frustrating to see. If you would like some help, you might start a thread asking for it.
I am still relatively new so I didn't want to say anything, but hear hear! I agree with you Dellet.

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