What is the effect of making a can longer?

[mr fixit]

Hypothetical scenario:

Let's assume that a can is made that works well. for the sake of argument lets say a 30Cal can, 1.5"od x 8" long with 7 60*cone baffles.
Let's then assume a second can is made with the same materials, and design, same baffle spacing, but in place of the end cap, the tube is 3" longer. (From the muzzle forward, the two cans are identical for the first 8"). I am assuming an end cap on the longer tube, not just an open tube at the end

What would be the effect on suppression of the longer can? Would there be any difference at all?

[cal50]

Cooling and slowing the expanding gas = suppression.
Since a longer can with more internal space (and likely baffles) the 2nd can should / will be quieter.


A recent example of this is the new line of suppressors with screw on / add on modules for added noise reduction.

[gunny50]

Cooling and slowing the expanding gas = suppression.
Since a longer can with more internal space (and likely baffles) the 2nd can should / will be quieter.
A recent example of this is the new line of suppressors with screw on / add on modules for added noise reduction.

These add on units do hold extra baffles.
Extra volume on the end withor baffles wil also give extra suppression but with 2 more baffles the suppression is more.

Gunny

[doubloon]

Not just an empty tube?

What about a ported empty tube? http://www.metrogun.com/how_it_works.html


Not Metro ...
https://www.youtube.com/watch?v=NxOg00iocv0

[cal50]

I have seen AR rifle length buffer tubes used as a suppressor for .22 rimfire ( no baffles) that actually worked well. It's volume did the job of containing the gas and releasing it.

Adding baffles slows and strips off heat.
There is a balance between size & effiency.

[mr fixit]

So, for the sake of understanding, (and assuming all legalities are followed ) taking a 7.62-sd and adding 6 inches with a single baffle end cap will only make it quieter or at worst no improvement, but not louder?

[noisecatcher]

I have had people tell me the tone of the can will vary depending on the length. But I have always questioned if it was the length or the extra baffles and volume. Of course the guys who can experiment with different designs without getting a stamp for each can aren't going to freely give out their method to make a deep tone because they are selling it to put food on their tables and buying shoes for the crumb snatchers.

[c5_nc]

So, for the sake of understanding, (and assuming all legalities are followed ) taking a 7.62-sd and adding 6 inches with a single baffle end cap will only make it quieter or at worst no improvement, but not louder?

It would be quieter for sure.

[quiettime]

I have seen AR rifle length buffer tubes used as a suppressor for .22 rimfire ( no baffles) that actually worked well. It's volume did the job of containing the gas and releasing it.
..

Someone I knew once took a 2 liter bottle and stuck it on the end of a bull barrel .22 pistol. That person was amazed how quiet it was, about like smacking the bottle against a hard surface.

But that's a bulky proposition. The art is to find the balance where another baffle or another inch doesn't really justify itself, and to make more efficient designs that work better in a tighter space.

[cal50]

I have had people tell me the tone of the can will vary depending on the length.

I think the tone can vary using different construction materials ( tube / baffles ) as well.
I bet the guys with the spiffy instrumentation know for sure.

[mr fixit]

.... The art is to find the balance where another baffle or another inch doesn't really justify itself, and to make more efficient designs that work better in a tighter space.

I ask because I have obligated myself to a 9" can at minimum. With that length added to my 8" barrel 300aac, I can perm. attach and have a 1 stamp gun. I was thinking if a good 300 can was say 7", and I had to have 9", I could just add 2 to the end. I wanted to make sure all would go well in that case.

[quiettime]

Specwar is 9" and is possibly the quietest 300 Blk can on the market. I think you're ok

[noisecatcher]

I think the tone can vary using different construction materials ( tube / baffles ) as well.
I bet the guys with the spiffy instrumentation know for sure.[/quote]

It would be nice to be able to try different set ups all day until you found what you wanted. On the other hand it would suck to pay the bills when all you've done for two months is use a lot of material and make 1 good suppressor and 19 ok/decent suppressors and 4 extremely elaborate paper weights.

[ghostdog662]

It's all about temperature of the gas when it exits.

It doesn't matter if it is longer necessarily. Properly worked gas will stay in the can longer and become cooler. This is why it pays to have a good design so you save weight, save length and increase your grin size.

The diminishing returns is why most people settle for a 7-9" length on modern cans.

[fastfire]

[quote="ghostdog662"]It's all about temperature of the gas when it exits.

It doesn't matter if it is longer necessarily. Properly worked gas will stay in the can longer and become cooler. This is why it pays to have a good design so you save weight, save length and increase your grin size.

The diminishing returns is why most people settle for a 7-9" length on modern cans.[/quote


Hot gas cold gas, does cold gas make or carry less sound than hot gas, really??
My thinking, the longer the sound stays in the can the sound is lessened or killed the less sound comes out.

I'm far from an expert but that's my thinking at this point.

[T-Rex]

It's all about temperature of the gas when it exits.

It doesn't matter if it is longer necessarily. Properly worked gas will stay in the can longer and become cooler. This is why it pays to have a good design so you save weight, save length and increase your grin size.

The diminishing returns is why most people settle for a 7-9" length on modern cans.

Hot gas cold gas, does cold gas make or carry less sound than hot gas, really??
My thinking, the longer the sound stays in the can the sound is lessened or killed the less sound comes out.

I'm far from an expert but that's my thinking at this point.

Read up on the Ideal Gas Law. Temperature is proportional to Kinetic Energy.
Allowing the gas to expand (read as cool) inside the tube, diminishes it's expansion rate when it exits the suppressor.
This action, alone, is what makes you pay the Tax Stamp.
A soda bottle, having no baffles but for the last wall, will suppress a shot by allowing the gas to expand inside.
Start adding baffles to disrupt the flow and you have a, more modern, suppressor.

The added volume will help, but why not add some more baffles, if you have the space? Weight reduction s not an acceptable answer

[mr fixit]

The added volume will help, but why not add some more baffles, if you have the space? Weight reduction s not an acceptable answer

I was really working from a theoretical standpoint, rather than a realistic one. I have my answer, that being "longer wont be a penalty to suppression". Now I can work on the realistic situation.

I think that a 1" or so free space at the end of the tube will add a bit of deeper tone perhaps.

It looks like a 9"x1.625"x.065" SS tube, direct threaded, with 10 freeze plug baffles when assembled to my 8" 300aac barrel and complete upper will be within 3 oz. of my 16" complete Colt 6920 upper. That makes the can heavy by our standards, but very acceptable to me in this instance.

[fastfire]

It's all about temperature of the gas when it exits.

It doesn't matter if it is longer necessarily. Properly worked gas will stay in the can longer and become cooler. This is why it pays to have a good design so you save weight, save length and increase your grin size.

The diminishing returns is why most people settle for a 7-9" length on modern cans.

Hot gas cold gas, does cold gas make or carry less sound than hot gas, really??
My thinking, the longer the sound stays in the can the sound is lessened or killed the less sound comes out.

I'm far from an expert but that's my thinking at this point.

Read up on the Ideal Gas Law. Temperature is proportional to Kinetic Energy.
Allowing the gas to expand (read as cool) inside the tube, diminishes it's expansion rate when it exits the suppressor.
This action, alone, is what makes you pay the Tax Stamp.
A soda bottle, having no baffles but for the last wall, will suppress a shot by allowing the gas to expand inside.
Start adding baffles to disrupt the flow and you have a, more modern, suppressor.

The added volume will help, but why not add some more baffles, if you have the space? Weight reduction s not an acceptable answer

Naturally as the gas leaves the heat source it will cool.
But if the gas were to enter a heated chamber(a really hot chamber) it would be louder than a cold chamber?
Going to read up on Ideal Gas Law now.

Update; read Ideal Gas Law, formulas just mess with my head, need it in layman's terms.

[T-Rex]

formulas just mess with my head, need it in layman's terms.

No problem.
Heat = Excitement
Yes, the gas will cool, overtime. The suppressor's design will expedite the expansion, leaving the gas with a less than potent kick.
Modern suppressor materials are chosen due to their ability to mitigate heat while preserving integrity.