Newbie 'M' baffle question

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AKCoyote
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Newbie 'M' baffle question

Post by AKCoyote » Tue Nov 20, 2018 5:12 pm

Morning gents. New to the site and just learning about home built cans. Built my first one from a mag light with K baffles for a .308 and was fairly impressed with the results. Everything is legal. Have my tax stamps etc.

Now I want to suppress a single shot Marlin .22 . The goal is to create a small game rifle so that in the event of a SHTF moment, I can hunt without drawing any attention. I live in Alaska but even here, stealth can be a concern.

So my question is, when using freeze plugs as baffles, why do they need to be formed as a 'M'? From my reading, there are 3 basics to suppressor efficiency. Bore tolerance. Baffles and volume. I'm curious why a configuration like this wouldn't work..........

=|____[][][][][]| Why is the 'M' configuration and stacking the baffles like this {{{{{{ more efficient?

Great site and I and I look forward to learning the whys and what fors!

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fishman
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Re: Newbie 'M' baffle question

Post by fishman » Tue Nov 20, 2018 5:45 pm

The short answer is:
Fluid dynamics is complicated.

The long answer is:
here

Cad is such a waste of money. This is way easier:

=[____]< ]< ]< ]< ]< ]
k baffles :D

=[____<_<_<_<_<_]
Cones

=[___<|=<|=<|=<|=]
Omegas

=[____{ { { { { { { { ]
Radials

=[_///////////]
Liberty Monocore

=[___/,\'/,\'/,\'/,\]
Gemtech G core

=[=====[__<_<_<_<_<_]
Integral

=[____(_(_(_(_(_]
Hemisphere baffles
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Re: Newbie 'M' baffle question

Post by 00goobs » Tue Nov 20, 2018 6:22 pm

Simple and visually effective. Thanks for the origonal post and reply...

Interesting video if you haven't seen it yet:

https://youtu.be/7pOXunRYJIw

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Re: Newbie 'M' baffle question

Post by AKCoyote » Tue Nov 20, 2018 7:40 pm

Interesting info. Thanks for the reply!

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John A.
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Re: Newbie 'M' baffle question

Post by John A. » Tue Nov 20, 2018 7:59 pm

There was a guy here years ago that used fender washers for baffles separated by some thin aluminum tubing for spacers.

Essentially, he bought fender washers that he could put down into his tube.

Then used a spark plug socket to lay the fender washer on.

In the center of the hole, he put a larger steel ball bearing (about 3/8" I think) and then he put it all in a vise and basically made the ball bearing press into the hole. This opens the diameter of the hole up some, and also swells the fender washer to the shape of the ball bearing.

I heard him use it a few times and it sounded pretty good. The thing with fender washers is the steel will last a lifetime, and the nickel or chrome plating does help prevent some of the build up.

found it:

https://www.youtube.com/watch?v=oSqQoagqG_E
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Re: Newbie 'M' baffle question

Post by AKCoyote » Wed Nov 21, 2018 5:54 pm

Thanks John!

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Re: Newbie 'M' baffle question

Post by Historian » Wed Nov 21, 2018 7:32 pm

00goobs wrote:Simple and visually effective. Thanks for the origonal post and reply...

Interesting video if you haven't seen it yet:

https://youtu.be/7pOXunRYJIw
Good empirical information on stress the first third of
a can's being subjected to. Likely that a SS hose clamp on
the back threads would have given some stability.

Sometime ago some folks were using carbon fibre tubes.
Whatever happened to this line of development?

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Re: Newbie 'M' baffle question

Post by 00goobs » Wed Nov 21, 2018 8:04 pm

Carbon fiber tubes should be easy if there are carbon fiber barrels out for the ARs. I am really interested in Titanium for the weight and visual when welded/blued....

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fishman
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Re: Newbie 'M' baffle question

Post by fishman » Wed Nov 21, 2018 8:16 pm

00goobs wrote:Carbon fiber tubes should be easy if there are carbon fiber barrels out for the ARs. I am really interested in Titanium for the weight and visual when welded/blued....
1. Silencers get way hotter than barrels do.
2. Carbon fiber WRAPPED barrels are a thing, not barrels made entirely from carbon fiber.
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Re: Newbie 'M' baffle question

Post by John A. » Wed Nov 21, 2018 8:43 pm

I think it's Ecco that is using carbon fiber tubes on some of his rimfire stuff. Another member and I were discussing it in PM a little while back too.

I think that I am going to stick with aluminum tubes for the time being.
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Re: Newbie 'M' baffle question

Post by 00goobs » Wed Nov 21, 2018 9:39 pm


AKCoyote
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Re: Newbie 'M' baffle question

Post by AKCoyote » Mon Nov 26, 2018 6:14 pm

Many, many moons ago I worked for a defense contractor that manufactured rocket motors. I worked in a burn lab where we tested solid rocket fuel for its burn rate characteristics and well as a research lab where we were developing carbon fiber rocket motors. This was in the day of the MX program. I can tell you from experience that there is nothing finer than a properly wound carbon tube or cylinder. It's light, strong and virtually indestructible by heat. If you ever get an opportunity to use a carbon cylinder for a can, I will assure you that you won't be disappointed.

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Re: Newbie 'M' baffle question

Post by 00goobs » Tue Nov 27, 2018 8:28 am

I believe there's a carbon-ceramic material used on brake rotors that get red-hot during heavy braking without deforming. I haven't seen the process, but would be interesting to try....

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Re: Newbie 'M' baffle question

Post by T-Rex » Tue Nov 27, 2018 1:10 pm

Since the OP questioned baffle layout and orientation, I thought it pertinent to note SilencerCo's Switchback 22lr, modular suppressor.

In the long configuration, barrels >10" saw a greater reduction with the second set of baffles arranged backwards :shock:


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John A.
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Re: Newbie 'M' baffle question

Post by John A. » Tue Nov 27, 2018 1:15 pm

Notice how in the reversed direction, the expanding gas would also be directed rearwards, instead of forward.

I have long believed that if you redirect the expanding gasses any direction besides the way it wants to go, that it will make it more quiet overall.

Also, in longer barrels (10") that allows more time for the powder to burn out, so that too should be considered. It's not just the silencer is making it more quiet because there is more going on that just that.
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Re: Newbie 'M' baffle question

Post by Capt. Link. » Tue Nov 27, 2018 1:32 pm

John A. wrote:Notice how in the reversed direction, the expanding gas would also be directed rearwards, instead of forward.

I have long believed that if you redirect the expanding gasses any direction besides the way it wants to go, that it will make it more quiet overall.

Also, in longer barrels (10") that allows more time for the powder to burn out, so that too should be considered. It's not just the silencer is making it more quiet because there is more going on that just that.
Those reverse baffles are similar to a Megaphone type of muffler exhaust where pressure is reflected and not sheared like a conventional baffle. A inline OOOOOOO monocore works like that.The OPS line of suppressors use the same principle.
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Re: Newbie 'M' baffle question

Post by Hard_ware » Tue Nov 27, 2018 10:03 pm

Not sure, but seems like the supersonic shock wave might have something to do with it.
Shorter barrels do not benefit from this configuration. The reduction is significant, especially keeping the same volumes and materials.

Would be interesting to see if adding some ablative material to the longer section of the suppressor would achieve a similar drop in db with normal full length configuration, this would indicate if its related to unburnt gasses. Knowing the reason for the reduction would be helpful in future designs.

My 22lr can looks like it wont have mini goblets inside, but little warped funnels that can be swapped around. :shock: .
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Re: Newbie 'M' baffle question

Post by Capt. Link. » Tue Nov 27, 2018 10:56 pm

Hard_ware wrote:Not sure, but seems like the supersonic shock wave might have something to do with it.
Shorter barrels do not benefit from this configuration. The reduction is significant, especially keeping the same volumes and materials.
The mixing of baffle types is not new but has always been applied logically :ie cones before ks to reduce pressures favored by k baffles. Reflective baffles have been used before as simple low grade baffles but who would have thought the effect was so great mixing them with high performance ones for a higher net loss than either could by themselves.

I suggest a parabolic baffle may provide the maximum reflection and thus effect.Using these with a K baffle may set new levels of performance.I would think that the spacing of the reflective element would be crucial to the tuning of the stack.Their may even be a application to use these with monocores to enhance performance. I know this may work best with a wet suppressor as the ablative would have more time in contact with the gases.......I'll be making chips in my sleep again thinking about this.
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Re: Newbie 'M' baffle question

Post by Hard_ware » Wed Nov 28, 2018 12:00 am

Yes k’s by muzzle, followed by parabolic in the mix might be interesting.
I would need to work on a jig for turning the parabola.
Would also be handy for small radius cuts.
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Re: Newbie 'M' baffle question

Post by DKDravis » Wed Nov 28, 2018 1:11 pm

There are at least two VERY different types of Carbon fibre "items" - The polymer-bound (usually epoxy, polyester or thermoplastic bound fibres) and the "Ceramic Carbonfibre"

The first types are dependent on the Tg or thermal deformation limit of the binding agent. There are specialized types of epoxies that will keep up to 90% of their yield strength at temperatures up to 300 - 400 degrees centigrade, but they ar VERY expensive and difficult to work with, and are not generally used for comercially available carbon tubing.

The "Ceramic Carbon" use a baked ceramic substrate to bind the carbon fibres, and the binding matrix can sometimes almost match the limits of the carbon fibres.

however the carbon fibres react with oxygen at temperatures from around 300 degrees C. This will degrade any fibres exposed to oxygen.

carbon fibre filament wound tubes or "vessels" will keep their "hoop strength" way beyond the melting point of epoxies and thermoplastics, so making suppressors out of high Tg filament wound CF tubing makes very good sense for low pressure rounds (subsonics) and for hunting suppressors where you are not firing long strings of shots at a fast pace.

CF tubing has even worse heat dispersion/transfer rates than Ti, so the outside of a "can" will be significantly cooler than the inside.

I have produced 180 degrees C. Tg tubing for some experimental suppressors, and I own and use an A-tec Carbon-2 can, that I use on my .376Steyr (a kind of "short&fat" version of .375 caliber) Even with full house loads (300 grain bullets at 2400 fps) the can does not heat beyond 180 degrees after two full mags at a rapid pace (8 shots in 20 or so seconds)

Presently I'm experimenting with "reinforcing" thin wall Ti tubing with a "wrapping" of Kevlar and Carbon fibre.. This will allow a very light weight high pressure rated can that will have a low level of mirage, since the outside will heat up slowly. The same limitations will apply, but from experience with motorbike exhaust systems, the combination will tolerate much higher temperatures than one would expect from the 180 degree Tg of the epoxy used. My Carbon "wrapped" Ti exhaust regularly runs well above 250 degrees without any lasting visible degrading of the CF layer-
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Re: Newbie 'M' baffle question

Post by John A. » Wed Nov 28, 2018 2:03 pm

^ I like that post.

Wrapping Ti tube was something that I had thought could be done. I'm sure I don't have the tooling and materials and know-how to do it, but that would be one way to achieve higher pressures than the Ti itself is rated for and without adding a ton of weight.

Confederate troops would often over-charge their cannons to get a little extra range because the barrels were wrapped with whatever they could find. Rope mostly.
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Re: Newbie 'M' baffle question

Post by LavaRed » Fri Nov 30, 2018 2:42 am

I made a parabolic baffle- carbon-fiber tube mini can years ago, in .22LR. It is my most silent.
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Re: Newbie 'M' baffle question

Post by a_canadian » Fri Nov 30, 2018 10:01 pm

I don't recall you having said you clipped those parabolic cones... Did you? I think they were extremely thin, and what, 3 of them in the tube? Something about the construction being rather fragile, at least in the first iteration... Spacer tubes too thin?

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Re: Newbie 'M' baffle question

Post by Historian » Fri Nov 30, 2018 11:20 pm

The good Captain's note contains a gem that could
easily go unnoticed:

"The mixing of baffle types is not new but has always been applied logically,
i.e., cones before ks to reduce pressures favored by k baffles.."

Let's analyze his seminal idea:

First, the blast chamber performs the yeoman's duty of rapidly
allowing initial expansion with a significant pressure reduction.

Aside: over the years smiths have expressed rules of thumb on the
ratio of blast chamber-length versus total suppressor length for some
calibers.. Any know of actual studies on the optimum
blast chamber length for each calibre, e.g., .22; .45, 9mm?

Second, M's, especially stepped M's, are next stage 'blast chambers' with
the introduction of delaying turbulence.

Third, with this gained reduced pressures over say ½ the tube the K's specialty
of acting as a 'line resistor' come into play.

We do know that a the famous PTK YouTube .22 suppressor made up
of all K's ... no info on blast chamber length ... in ~ 9.5" tube produced
an enviable 'pellet gun' sound.

When HPA passes it will allow empirical testing of these variables.

Thank you CL for highlighting this issue.


Best.

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Re: Newbie 'M' baffle question

Post by LavaRed » Sat Dec 01, 2018 1:18 am

a_canadian wrote:I don't recall you having said you clipped those parabolic cones... Did you? I think they were extremely thin, and what, 3 of them in the tube? Something about the construction being rather fragile, at least in the first iteration... Spacer tubes too thin?

Two of them got accidentally dented, and it improved the performance drastically, so I left them like that. It's 3 parabolas mounted on strips. Everything is 1/32" thick. The trick to not breaking the core is to clean it every 2 to 4 magazines so that it doesn't stick. Hardly practical, but for a super small gun, one will hardly use that many shots.
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