My new Form 1 build

@MistWolf @Clint

Here's a sketch of the internals. Pretty self explanatory.

https://i.imgur.com/ph0zyIu.png

All but the first baffle single clipped. At 5.5" it's not exactly a K can, but it's still shorter than average, and lighter.

So far I've only tried it on my Mk18 upper. I need to remove my 6920's flash hider so I can try it on the 16 inch, which is what my SOT tested it with.

I took a few shots sans ear pro, and it wasn't exactly pleasant, but also not painful either. But the port pop alone on a 10.3 is way past hearing safe anyways. My SOT went sans ear pro with his 16 inch upper, and he indicated it was hearing safe based on comparing it to a factory can that is a known quantity. Part of that could of course be the tone, so I wouldn't want to do that very often without good sound metering equipment to back it up.

On my Mk18, I might compare it to maybe shooting a 9mm pistol in terms of discomfort. Part of what makes me think I'm mostly hearing port pop is that I tried it with and without the distal cone (using a longer spacer in the blast chamber), and there was no notable difference, which you would expect there to be. I think once I do the same side by side comparison in both configurations on my 16" upper it's going to become apparent that there's a difference. If not I will just lose the distal cone and let the gasses from the coaxial chamber go straight into the distal space. My endcap of choice has some nice stepping, so that should help.

I also need to get out the nods and see what difference it makes for flash. Word on the street is that coaxials somehow reduce flash via some mechanism I've yet to grasp. Would be very cool if there was a notable reduction.

I can also move that unported cone anywhere in the stack, so I might try different positions and see what effect it has on backpressure.

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Originally Posted by okie

I can also move that unported cone anywhere in the stack, so I might try different positions and see what effect it has on backpressure.

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Please do.

That's no garden variety F1 can, with coaxial bypass.

Nice job Okie!

Is this a kit or self design?

Materials?

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Originally Posted by okie

Here's a sketch of the internals. Pretty self explanatory.

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Originally Posted by Clint

That's no garden variety F1 can, with coaxial bypass.

Nice job Okie!

Is this a kit or self design?

Materials?

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It's a hodgepodge of off the shelf solvent trap parts. That market is getting really good! With a little basic understanding of how silencers work the average person can put together a pretty good can to meet most needs, whether that be pistol, rimfire, or centerfire rifle. I think this style fits the needs of centerfire SBRs extremely well. It's a good balance between weight, length, suppression, and backpressure mitigation.

The thread adapter and endcap are SPC, the tube is SPC, and the cones are VVT. I got the spacing material off a guy on the form 1 forum.

When I think back to what was state of the art for 1978, the fact that people are now home rolling designs like this, it must be what bi plane fliers felt like watching us go to the moon in 69.

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Originally Posted by SteyrAUG

When I think back to what was state of the art for 1978, the fact that people are now home rolling designs like this, it must be what bi plane fliers felt like watching us go to the moon in 69.

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Yea we've come a long way from maglites and freeze plugs. Amazing how much innovation people are capable of when the government makes you wait six months to two years for a freaking gun muffler.

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Originally Posted by okie

Yea we've come a long way from maglites and freeze plugs. Amazing how much innovation people are capable of when the government makes you wait six months to two years for a freaking gun muffler.

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So I can remember wipe and mesh technology. I can remember about mid 80s when Doc Dater changed the game for everyone for all time. Now most of that stuff is pretty old hat.

Now that $200 isn't nearly as cost prohibitive for serious gun guys, suppressors have become "common usage" and that is really driving the tech. By contrast, machine gun tech has gone almost nowhere because private sector advances came to an end in 1986. KAC kicks out an interesting design now and then but there is no across the board revelations other than make it out of polymer and add rails.

Suppressors are not only smaller and more efficient, they are now in many cases user serviceable which was a unicorn dream not very long ago.

I can still remember hanging a sionics can almost as long as the rifle itself on a M-16 and thinking "there has to be a better way."

That looks amazing.

I would shorten the blast chamber spacer and put another in another baffle (shortening the blast chamber)...should help with FRP.

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Originally Posted by eodinert

That looks amazing.

I would shorten the blast chamber spacer and put another in another baffle (shortening the blast chamber)...should help with FRP.

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I wasn't able to detect any first round pop, even in the five baffle configuration. Might be because of the coax chamber, I don't know. Might also become more obvious when I shoot it on the sixteen inch rifle.

Ah, reading it again I see you said 'port pop' and not 'first round pop'. Hooked on phonics didn't work for me.

You may want to try moving the unported "transfer" baffle to position #4.
The theory being more disruptive mixing early in the stack and a little less direct path out for the bypass flow.

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Originally Posted by okie

I can also move that unported cone anywhere in the stack, so I might try different positions and see what effect it has on backpressure.

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Originally Posted by 1168

Please do.

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Originally Posted by okie

https://i.imgur.com/ph0zyIu.png

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Originally Posted by Clint

You may want to try moving the unported "transfer" baffle to position #4.
The theory being more disruptive mixing early in the stack and a little less direct path out for the bypass flow.

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Definitely plan on trying different positions. Funny thing though...

I actually had my SOT cut two blast chamber spacers. The one you see in the drawing, and a longer one that lets me run the can without the unvented baffle. So the unvented baffle at the end is removed completely, and the other baffles move up.

I wanted to see what the difference was between letting the gas recombine vs. just letting it vent directly into the distal chamber.

I've already tried both configurations, and I couldn't tell any difference whatsoever. I wish I had a good sound meter though. I would be very interested to know if there's any measurable difference.

But it's got me wondering if it simply doesn't make any difference where the coaxial chamber vents to. The gas is going to come out the end one way or another. I think by keeping pressure in the coaxial chamber low it encourages gas to leave the laminar column and go around. Because once the can reaches equilibrium, the laminar column will just go straight through. By keeping the resistance in the coaxial chamber lower, you're always ensuring that the path of least resistance is not the one straight out the bore.

I've never found suppressors to sound much different at all. The only can, out of a dozen or so that we run regularly, that sounds noticeably different is the 762Sdn on the 308 bolt gun. That sucker is louder.

When we did an F1 kit, the thing I did, which didn't pan out, was leave a roomy blast chamber. Cutting metal without good machine shop resources is exhausting. So you talk yourself into the idea that 5 baffles is enough. But as I posted before, I had to go back in and add a baffle and some clips to the existing baffles.

It's really hard to predict what will happen due to the complex dynamics at play.

It's anybody's guess and it comes down to testing to find out.


One reason there may not be a perceptible difference between the two configurations, is the port pop may be dominating the at ear sound levels.

With an unmodified gas system, the sound levels from from the gas piston venting can easily be 140-150 dB at the ear, completely masking the 130-140 dB at the muzzle.

Once the gas is dialed down, it may be easier to detect differences.

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Originally Posted by okie

I've already tried both configurations, and I couldn't tell any difference whatsoever. I wish I had a good sound meter though. I would be very interested to know if there's any measurable difference.

But it's got me wondering if it simply doesn't make any difference where the coaxial chamber vents to. The gas is going to come out the end one way or another. I think by keeping pressure in the coaxial chamber low it encourages gas to leave the laminar column and go around. Because once the can reaches equilibrium, the laminar column will just go straight through. By keeping the resistance in the coaxial chamber lower, you're always ensuring that the path of least resistance is not the one straight out the bore.

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Originally Posted by markm

I've never found suppressors to sound much different at all. The only can, out of a dozen or so that we run regularly, that sounds noticeably different is the 762Sdn on the 308 bolt gun. That sucker is louder.

When we did an F1 kit, the thing I did, which didn't pan out, was leave a roomy blast chamber. Cutting metal without good machine shop resources is exhausting. So you talk yourself into the idea that 5 baffles is enough. But as I posted before, I had to go back in and add a baffle and some clips to the existing baffles.

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A silencer without clips is basically a big heavy expensive muzzle brake.

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Originally Posted by Clint

It's really hard to predict what will happen due to the complex dynamics at play.

It's anybody's guess and it comes down to testing to find out.


One reason there may not be a perceptible difference between the two configurations, is the port pop may be dominating the at ear sound levels.

With an unmodified gas system, the sound levels from from the gas piston venting can easily be 140-150 dB at the ear, completely masking the 130-140 dB at the muzzle.

Once the gas is dialed down, it may be easier to detect differences.

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That's what I'm wondering, too. Just need to get off my but and remove the flash hider on my 16 inch so I can give that a try.

it would be interesting to run the tests on a bolt gun or shut off the gas completely. No port pop at all.

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Originally Posted by hi-wayman

it would be interesting to run the tests on a bolt gun or shut off the gas completely. No port pop at all.

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That's the proper way. Should probably get a 223 bolt gun since apparently this is my new obsession now.

NFA enhanced BRD...

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Originally Posted by okie

That's the proper way. Should probably get a 223 bolt gun since apparently this is my new obsession now.

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Originally Posted by Clint

NFA enhanced BRD...

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Oof. Why couldn't I have been born in New York where they don't have to worry about such things.

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Originally Posted by markm

I've never found suppressors to sound much different at all. The only can, out of a dozen or so that we run regularly, that sounds noticeably different is the 762Sdn on the 308 bolt gun. That sucker is louder.

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Man, I have. In the last 20 years I've seen / heard add on cans get as quiet as MP5SD setups with the correct ammo. That is pretty amazing to me. 20 years ago you could get a .22 that quiet, not 9mm or any other handgun round.

Using standard 5.56 and .308 still gives you a ballistic crack and it will never be "pew pew" quiet, but we have come a long way. The Ti cans are also a lot lighter. Cans that almost tame 5.56 and .308 have gotten smaller and lighter.

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Originally Posted by okie

A silencer without clips is basically a big heavy expensive muzzle brake.

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I disagree. I've seen the freeze plug baffles that work just like a clipped baffle stack.

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Originally Posted by SteyrAUG

Using standard 5.56 and .308 still gives you a ballistic crack and it will never be "pew pew" quiet, but we have come a long way.

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That's it. Most of our shooting is 300WM, 6.5CM, 7.62, and 5.56mm. Differences are barely noticeable for the most part. Of course the 300WM is a little thumpier, but like I said... for whatever reason, the 762sdn is the only one that raises an eyebrow for being barkier than the rest.

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Originally Posted by markm

I disagree. I've seen the freeze plug baffles that work just like a clipped baffle stack.



That's it. Most of our shooting is 300WM, 6.5CM, 7.62, and 5.56mm. Differences are barely noticeable for the most part. Of course the 300WM is a little thumpier, but like I said... for whatever reason, the 762sdn is the only one that raises an eyebrow for being barkier than the rest.

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Most people clip freeze plugs. There are some silencers that use alternate methods like ports in the baffles, but it doesn't work very well. The name of the game is to install the can, sight it in, and don't take the can off after that.

Didn't PB do a F1 can without clips that was noticeably louder than normal?

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Originally Posted by markm

I disagree. I've seen the freeze plug baffles that work just like a clipped baffle stack.

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I think the best way to visualize it is to think of the gas coming out of the barrel like water comes out of a hose. That concentrated, high pressure column is what hits the atmosphere and makes the waves that you hear as sound. By breaking up that column, you lower the pressure and velocity of the gas before it hits the atmosphere, and therefore lower the resulting pressure wave.

Problem is, you can't put anything in that column's path to break it up, because that's where the bullet comes out, too. So you have to create a pressure differential in the can to encourage the gas to flow in one direction, causing the column to bend slightly, driving it down into the baffles.

People have tried alternate methods of interrupting the column, namely by using ports in the baffles to try and create jets of gas that aimed at the column are intended to disperse it. The problem with that is that the gas routed through those ports is already at a much lower pressure, so it's like trying to break up the laminar flow out of a fire hose with a squirt gun.

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Originally Posted by Clint

Didn't PB do a F1 can without clips that was noticeably louder than normal?

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Yep. I did the work. That kit had baffles that just looked inefficient... less conical in shape than I'd like. The company had nice baffles on their site after we bought and finished the kit. But I built it with, I think, 5 of the baffles un-modded; just bored out. And it was louder than a can should be.

I pulled it apart and added a 6th freeze plug baffle and some sloppy clips to the existing baffles. The can sounded like the rest of the batch after that.

Yes, it seems the asymmetric clips help "steer" that column off axis in a similar manner to which a lens bends light.

Stack a few in a row and you can get some good deflection.

Seven baffles seems to be a good default number, but various designs have more or less.

Clip example Rugged Obsidian 45 for reference:
https://content.osgnetworks.tv/firea...pressors-8.jpg

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Originally Posted by okie

I think the best way to visualize it is to think of the gas coming out of the barrel like water comes out of a hose. That concentrated, high pressure column is what hits the atmosphere and makes the waves that you hear as sound. By breaking up that column, you lower the pressure and velocity of the gas before it hits the atmosphere, and therefore lower the resulting pressure wave.

Problem is, you can't put anything in that column's path to break it up, because that's where the bullet comes out, too. So you have to create a pressure differential in the can to encourage the gas to flow in one direction, causing the column to bend slightly, driving it down into the baffles.

People have tried alternate methods of interrupting the column, namely by using ports in the baffles to try and create jets of gas that aimed at the column are intended to disperse it. The problem with that is that the gas routed through those ports is already at a much lower pressure, so it's like trying to break up the laminar flow out of a fire hose with a squirt gun.

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Originally Posted by Clint

Yes, it seems the asymmetric clips help "steer" that column off axis in a similar manner to which a lens bends light.

Stack a few in a row and you can get some good deflection.

Seven baffles seems to be a good default number, but various designs have more or less.

Clip example Rugged Obsidian 45 for reference:
https://content.osgnetworks.tv/firea...pressors-8.jpg

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My working theory is it's not so much about how many baffles there are but more about how long the can is. You see a lot of factory cans with 3 baffles, and the first is generally more along the lines of a blast diffuser. Then you see other factory cans that have like 20 baffles. The common theme though is the long ones are quiet and the short ones are loud.

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Originally Posted by Clint

Seven baffles seems to be a good default number, but various designs have more or less.

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It's weird. We shoot the sig cans that have like a dozen baffles, and then I have an M4-1000 that has 4 baffles... from the shooter position, they're not THAT different.

Pappabear also has the Mini KAC 556 can.. and that one is a little barky. But for the size of it, you can't complain.

Yes, there is considerable variation in the number of baffles.

The TurboK is amazing for what it is and only has 3.

https://yhm.net/media/catalog/produc...28_hires-2.jpg

I like the smaller cans on Gas guns. It's a little louder off the gun, but the lower back pressure seems to make the port snap a little less noisy so it actually seems quieter to me in the shooter position on the few I've shot.

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Originally Posted by markm

I disagree. I've seen the freeze plug baffles that work just like a clipped baffle stack.



That's it. Most of our shooting is 300WM, 6.5CM, 7.62, and 5.56mm. Differences are barely noticeable for the most part. Of course the 300WM is a little thumpier, but like I said... for whatever reason, the 762sdn is the only one that raises an eyebrow for being barkier than the rest.

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Isn't that an Ops Inc can? If so, revolutionary for the time and still pretty robust but probably a dated design at this point.

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Originally Posted by SteyrAUG

Isn't that an Ops Inc can? If so, revolutionary for the time and still pretty robust but probably a dated design at this point.

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Last I saw the Surefire cutaways, they were effectively an fancy freeze plug type stack. I could be senile, but I don't remember their cans being heavy on the clipped feature at all.