Thread: Barrel length vs suppressor length

From what i’ve messed around with, an 18” barrel with 8 DPT baffles (24” overall length) will be a heck of a lot quieter then a 20” barrel with 4 DPT baffles (24” overall length).

Originally Posted by Hunter_Nick

In starting this thread I was referring to my 358. It’s fairly loud at 20” and 4 baffles even though the 2219 powder is 100% burnt by the muzzle. I’m just going to try another baffle (or two) and go from there. It might just be a function of the large bore diameter rather than anything else.

Try ss blast baffle to begin with.they seem to make sizable difference.

Originally Posted by Hunter_Nick

In starting this thread I was referring to my 358. It’s fairly loud at 20” and 4 baffles even though the 2219 powder is 100% burnt by the muzzle. I’m just going to try another baffle (or two) and go from there. It might just be a function of the large bore diameter rather than anything else.

Agree, bigger bore likely result in less suppression for same number of baffles. Gunworks do a "pig hunter special" 44 mag suppressed, and that has a pretty substantial suppressor, 8" forward, 4" back...https://www.gunworks.co.nz/shop/item...ressed-pig-gun

I do think that longer barrels are quieter for the shhooter and possibly for sidestanders too. A big reason for more suppressors use nowdays is the use of short ( sub 24 ) barrels; my opinion.
Common sense is that extra suppressor will reduce nose more than extra bare barrel but of course theres a big weight penalty before the suppressor even gets in front of the muzzle.
Another advantage of extra barrel length is 25 fps for each inch. Sone try to make up for shortness by using a bigger cartridge . Hence the 300 WSM superpigs … their new owners little anticipating how many extra inches of suppressor they will then carry to compensate for a short tube.

We might have some tests results somewhere that we did in the past, but we ll have to dig them out.

I don’t think you get much advantage to cutting below 15” and adding extra baffles in a 308, if you are using a standard over barrel suppressor,
Any shorter and if you want some descent sound suppression you would have to start with a magnum rear chamber which in turn involve scalloping the stock in most cases.
Look up Tikka 14” in the following link:

https://www.dpt.co.nz/gallery/

And you can see the magnum over barrel suppressor right back inside the stock.

For a 300 blackout ,357 or 44magnum, specially in subsonic, and for an equal overall length, you would benefit from cutting very short and going with a muzzle forward with extra baffles, compared to keeping the barrel longer and going with a standard or magnum over barrel with less baffles , due to the smaller quantity of powder in these cartridges.

Of course , in all cases, the longer the barrel, the less noise it makes due to a diminishing pressure at the muzzle and the muzzle being further from your ears.

Originally Posted by Hunter_Nick

Has anyone seen or done any research into whether it’s better to have an extra inch of barrel or an extra inch of suppressor forward of the muzzle for best noise reduction?

It has been proven that more suppressor in front of the muzzle suppresses noise better, but if you wanted a ‘fixed’ total length of barrel plus suppressor, are you better to go 18” barrel and 6 baffles? Or 20” barrel and 4 baffles?

Obviously there’s a velocity difference, but not a consideration at this stage. Just the noise

An extra inch of suppressor provides significantly more sound reduction than an extra inch of barrel. For example, 7 baffles on an 18-inch barrel ends up about the same overall length as 4 baffles on a 20-inch barrel — but the 7-baffle setup will be noticeably quieter.

Originally Posted by DPT

An extra inch of suppressor provides significantly more sound reduction than an extra inch of barrel. For example, 7 baffles on an 18-inch barrel ends up about the same overall length as 4 baffles on a 20-inch barrel — but the 7-baffle setup will be noticeably quieter.

data... I want data! Be great if say a suppressor manufacturer could give us some hard numbers...

but I understand the kit needed to measure such a thing would be potentially prohibitively expensive (or data could be commercially sensitive?)

Originally Posted by bjp

data... I want data! Be great if say a suppressor manufacturer could give us some hard numbers...

but I understand the kit needed to measure such a thing would be potentially prohibitively expensive (or data could be commercially sensitive?)

We have data, but it’s not practical to test every possible combination someone might suggest. There are simply too many variables involved.

If you have an extra 1 inch of barrel, that's effectively a baffle that's only got the volume of a 1" long .3" diameter cylinder.

If you have an extra suppressor baffle, it's going to have a lot more volume than that.

So a shorter barrel and more suppressor will be quieter for the same total length.

Originally Posted by gimp

and if you compare the 16" barrel, with suppressor, to the 20" barrel without........ ????

Great question. It's all subjective as I don't have the kit to measure sound (I tried a few phone apps but they sucked).
But the difference wasn't as much as you would think.
Suppressing the 20" barrel there was a noticeable difference, the 16" not so much.
This was a few years ago so maybe my memory is playing tricks, I was surprised at how ineffective it was.

I am just guessing but I think effectiveness is going to be linked to how much powder is burnt in the barrel. Someone smarter than me must be able to explain what's going on

Originally Posted by Sh00ter

I am just guessing but I think effectiveness is going to be linked to how much powder is burnt in the barrel.

The bigger the pressure differential between outside air and the muzzle, the louder the noise. Sound waves are pressure waves propagating through the air after all.

Peak pressure happens pretty rapidly. Like within the first 6" of barrel for most rifle rounds - regardless of whether you use a faster or a slower powder. And from that point on the pressure is tailing off. If you have a faster burning powder that is "100% burned" before muzzle exit, then it's tailed off quicker than the slower one which still has a little bit of puff left.

The difference isn't huge, probably hundreds of PSI rather than thousands in something like 308. The pressure behind the bullet certainly doesn't just disappear the moment the powder reaches 100% burn - and I'm not convinced that any unburned powder increases the noise by combusting with fresh air on the way out. I've been shooting a 9mm with a 13" barrel. The powder is "100% burned" in the first few inches - yet there's still a bit of a muzzle flash without a suppressor.

So powder burn rate is linked. But you can raise or lower muzzle pressure by loading hotter or milder with the same powder too. So it's not the only thing.

Originally Posted by Sh00ter

Great question. It's all subjective as I don't have the kit to measure sound (I tried a few phone apps but they sucked).

Use an external microphone and the ph apps work well. Even the wireless ones.

If only it was that easy….

Just shot my guns and at rifle my 17”223 sounded louder than my 243 with 22” barrel using same suppressor, never thought about short barrel made it so much louder


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Originally Posted by bjp

data... I want data! Be great if say a suppressor manufacturer could give us some hard numbers...

but I understand the kit needed to measure such a thing would be potentially prohibitively expensive (or data could be commercially sensitive?)

This is not new but suppressor tech hasn't changed much

https://d347awuzx0kdse.cloudfront.ne...sor%20TEST.pdf

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