Rules for making a 12ga silencer

Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.

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motus
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Rules for making a 12ga silencer

Post by motus »

Hello, brand new to weapons and silencers, trying to make some for my shotguns so that practice shooting is more comfy.

It seems that the calibre determines everything about the silencer, I stumbled on this table but the 12ga is missing.

Image
Image
What do I need to know to make the flute/pierced pipe type of silencer ?

And for the chambers/baffles type ?
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Fulliautomatix
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Re: Rules for making a 12ga silencer

Post by Fulliautomatix »

I don't know the answer to your question, but that drawing baffles me.

Assuming the measurements shown are supposed to be in inches, they recommended:
- a .375" ID pipe for a .452" projectile
- a .25" ID pipe for a .357" projectile
- a .25" ID pipe for a .356" projectile
- a .25" ID pipe for a .311" projectile
- a .125" ID pipe for a .22" projectile

That's just not going to work.

What's a flute/pierced pipe suppressor? (Guess I'll have to google that :P )

Looks like it might be a better flash suppressor, or possibly something as the basis for an integral suppressor design... but those diameters make my brain hurt.

Ok, after googling... it looks like this sort of thing is intended for airsoft/paintball guns. However that image shows 'real' firearm calibers.
http://www.wikihow.com/Make-a-Suppressor
http://www.tkoverkill.com/showthread.php?tid=874
Last edited by Fulliautomatix on Fri Oct 21, 2016 10:04 am, edited 1 time in total.
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motus
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Re: Rules for making a 12ga silencer

Post by motus »

Yes they are inches so I suspect the data came from some English document even if the blog post is in French http://survivreauchaos.blogspot.fr/2014 ... te-12.html

A flute/pierced pipe suppressor is the name I gave from what it looks like. You enclose that inside a bigger tube and you've got your basic suppressor.

So if those numbers are nonsense (which would be surprising), what is the rule for designing any suppressor ? Surely the calibre must count.

I found a bunch of books on archive.org (such as More Workbench Silencers by George Hollenback) but haven't read them yet.
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Re: Rules for making a 12ga silencer

Post by T-Rex »

I would clean your slate and start with a fresh page.
Plenty of designs out there that will prove to be far superior to that which you've shown.
What are your skills and do you have access to machining equipment?
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Re: Rules for making a 12ga silencer

Post by motus »

I'm not engineer but I can manage to build stuff. I already bought a copper pipe and some PVC, I was just waiting to know the size of the holes to drill but now you guys say forget it.
I have a vertical drill, stuff to cut and glue, and a 3D printer. There's a fablab in town where I suppose I could have some metal parts machined. But I want to keep it simple and cheap for the first one.
Biggest challenge would be to fix it to the barrels which are not all bored.
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Re: Rules for making a 12ga silencer

Post by propeine »

motus wrote:I'm not engineer but I can manage to build stuff. I already bought a copper pipe and some PVC, I was just waiting to know the size of the holes to drill but now you guys say forget it.
I have a vertical drill, stuff to cut and glue, and a 3D printer. There's a fablab in town where I suppose I could have some metal parts machined. But I want to keep it simple and cheap for the first one.
Biggest challenge would be to fix it to the barrels which are not all bored.
STOP and read for a month or 3. You're headed down a very dangerous path with copper and PVC. Nobody wants you to blow your face off.

I don't know if that website is trolling or ran by 10yr olds but that's the kind of crap you find in the anarchists cookbook. It isn't the end of the world. You don't need one TODAY from what you can find around the house.
Last edited by propeine on Fri Oct 21, 2016 11:59 am, edited 1 time in total.
Zombie1969
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Re: Rules for making a 12ga silencer

Post by Zombie1969 »

That looks like certain death. I'm new myself but knowing mufflers that's a flow through glass pack design. A pipe within a pipe with a packing material between the two like fiber glass or SS billow pad type material. People generally install that type if muffler to make more noise although it would be interesting to see or hear how it works on a gun.
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Re: Rules for making a 12ga silencer

Post by motus »

Well show me the real deal then, cause all what I found until now seems to be what you advise against.
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Re: Rules for making a 12ga silencer

Post by Zombie1969 »

Google shot gun suppressor. Try finding one that's taken apart showing the internals. I would assume there being used with slugs but I really don't know for sure so they should be a lot like a riffel suppressor.
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Re: Rules for making a 12ga silencer

Post by motus »

Zombie1969 wrote:Google shot gun suppressor.
Exactly what led me to the page above.

Those of you who already know the right stuff, please share.
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Re: Rules for making a 12ga silencer

Post by propeine »

motus wrote:
Zombie1969 wrote:Google shot gun suppressor.
Exactly what led me to the page above.

Those of you who already know the right stuff, please share.
http://www.thefirearmblog.com/blog/2014 ... -salvo-12/

Search the threads here. There are some homemade 12ga suppressors in the smithing forum as well.
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Re: Rules for making a 12ga silencer

Post by Fulliautomatix »

By the way, I don't see it mentioned above, but since you are self admittedly brand new to this. All technical reasons aside, DO NOT make a suppressor or suppressor parts until you have completed a Form 1 and have had it approved by the ATF.

Reference: http://nfatalk.org/forum/showthread.php?t=13974
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Re: Rules for making a 12ga silencer

Post by T-Rex »

Here is an example, from one of our members. There's actually 2 shotgun suppressors in that thread.

I recommend you do not "keep it simple and cheap for the first one". You need a $200 stamp for everyone you build so why not do the first one correctly.
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Re: Rules for making a 12ga silencer

Post by a_canadian »

motus wrote:So if those numbers are nonsense (which would be surprising), what is the rule for designing any suppressor ? Surely the calibre must count.
Calibre certainly counts, but look at the figures for 'C' compared to each projectile calibre. Those numbers are completely ridiculous. How is a 0.22" bullet supposed to get through a 1/8" hole in a pipe? Or a .45" through a 3/8" hole? These suggestions make no sense. The pipe must be larger than the gun's bore, not smaller. And leaving those silly numbers aside, the drawing looks almost entirely ineffective for suppression. The holes would need to be significantly larger to vent effectively.
motus wrote:I found a bunch of books on archive.org (such as More Workbench Silencers by George Hollenback) but haven't read them yet.
Of the few books on the subject worth looking at are the pair from Paulson. Even those don't really deliver much in the way of progressive information for a builder, more of a thorough history lesson. A friend lent me a handful of DIY silencer building books and I had a few good chuckles, as they echoed a few of my very early primitive attempts only with worse workmanship for the most part. Your best bet to learn about making these things is to study this forum, especially the completed builds thread:

viewtopic.php?t=79895

I just had a look through the PDF of the Hollenback book. Wow. Really awful stuff. Beginning to end it displays a string of terrible ideas. Plastic plumbing parts, lots and lots of tape, band clamps... it's laughable when considering the pressures involved with the weapons shown. A recipe book for injuries or worse.
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Re: Rules for making a 12ga silencer

Post by motus »

What surprises me more than most of the published designs being risky, is the apparent total lack of decent guides on how to make a decent silencer !

If at least there was a CAD file available I could manage to find a place where to have the parts made, but spending months to learn how to make a silencer is asking too much from me.
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Re: Rules for making a 12ga silencer

Post by a_canadian »

As I and others have suggested, a few hours spent looking at the completed builds here is going to give you Mich better insight into what sorts of builds work than if you read all those self-published plumber's silencer books. If you really don't want to learn, why ask? The thing you showed above is not only unlikely to suppress at all, but dangerous if made of the materials you've suggested. Glue and plastic? Just no. If that's nit the answer you wish to hear, well, we can't help you.
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Re: Rules for making a 12ga silencer

Post by whiterussian1974 »

Try using a 2" ID/2.125" OD tube w conical chrome-coated SS washers. Place 9 SS "guide rods" through the boreholes to squeeze the wad cup. That's your best bet.

Or use a monocore like they do in Europe. You could drill vent holes in your barrel and sump them into a coaxial space separated by washers. That would be easiest. Use a dedicated replacement barrel for your Base tube. That is probably easiest, and should be "good enough" for a Noob.

My 1st suggestion is for those w the skills to tack weld w Mig/Tig. Then file off the extra material. It's "state-of-the-art" for SilCo's modular design. They of course have better Mnfr'g skills and a better Production Model. ;)
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Re: Rules for making a 12ga silencer

Post by motus »

whiterussian1974 wrote:Try using a 2" ID/2.125" OD tube w conical chrome-coated SS washers. Place 9 SS "guide rods" through the boreholes to squeeze the wad cup. That's your best bet.
Okay, but what do I enclose this inside ? Any large metal pipe is going to be very heavy, hence why automobile mufflers were used. I saw a design with a maglit, but that's not for shotguns.

What's the advantages of the chambers VS simple holes design ?

Also, I don't see why you guys think copper and PVC is going to blow up.
As long as the end of the tube is open, that's where most of the pressure will escape from, unless the holes are too large. They can't be too small either or it won't silence anything, so how many holes of what size do I need to make ?
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Re: Rules for making a 12ga silencer

Post by fishman »

motus wrote:Also, I don't see why you guys think copper and PVC is going to blow up.
As long as the end of the tube is open, that's where most of the pressure will escape from, unless the holes are too large. They can't be too small either or it won't silence anything, so how many holes of what size do I need to make ?
Pvc isn't designed to handle high pressure. Pvc bursting is nasty, you won't want to be anywhere near it. 2" Pvc can burst at as little as 800psi. Firearm pressures can reach 60,000 psi. More realistically silencer pressures won't get that high but they can and will be several thousand PSI. Like you said, you are not an engineer, I am. Don't use pvc! Copper might not be as detrimental, but it will not last long. I'd be amazed if you got 50 shots through before it destroyed itself and possibly does damage to your gun or you.
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Re: Rules for making a 12ga silencer

Post by T-Rex »

2" Sch80 pvc pipe and 2" 18ga exhaust tubing will be close in weight- lb/ft.
At 110F (damn near ambient temperature for some areas), PVC looses half its strength, HALF!

Copper weighs and costs more than steel so I'm not sure of your point on this one.

You came here for information to build something.
Several people have tried to explain the correct ways.
For whatever reason, you do not wish to listen.

Please, be safe and legal, whichever road you choose.
Best of luck.
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Re: Rules for making a 12ga silencer

Post by Zombie1969 »

The pressure and immanent destruction of a copper and plastic suppressor aside. Think about the heat generated. That alone will destroy the pcv in no time and copper distorts and warps when heated and can cause a major obstruction in the bore. Then there's the fact that copper is soft to begin with. Simple common sense should lead you off that path.
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Re: Rules for making a 12ga silencer

Post by motus »

Okay I'll go back to the hardware store and see if they have steel parts.

Nevertheless I still don't know about the holes to drill...
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Re: Rules for making a 12ga silencer

Post by a_canadian »

Haven't built one, but from what I've seen in UK shotgun builds using the pierced tube within a tube design (with or without baffles outside the pierced tube) they tend to be about 1/8" and about 8 or 10 holes per inch, staggered, not in linear arrays.
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Re: Rules for making a 12ga silencer

Post by whiterussian1974 »

motus wrote:
whiterussian1974 wrote:Try using a 2" ID/2.125" OD tube w conical chrome-coated SS washers. Place 9 SS "guide rods" through the boreholes to squeeze the wad cup. That's your best bet.
Okay, but what do I enclose this inside ? Any large metal pipe is going to be very heavy, hence why automobile mufflers were used. I saw a design with a maglit, but that's not for shotguns.

What's the advantages of the chambers VS simple holes design ?
The 2" ID/2.125" OD tube is the container. The conical washers are the baffles. If you port the barrel, you won't need the guide rods. You simply mount Grade 5 Titanium or 304 Stainless, or even 6061-T6 Aluminum Seamless Tubing. (Make sure that "seamless" isn't just edges rolled together to join them. That creates a weak seam that will split under pressure.)

If you use the ported barrel, the purpose of the baffles is to trap the higher pressures at the earlier compartments so that each stage has lower pressure gas to expand. This is called "dwell." Dwell allows the lower pressure end gasses to vent before the early sections dump their gas pockets back into the bore for venting to atmosphere. This "smooths" the exhaust to lower pressure over longer time resulting in less peak sound generated. It sounds more like a hiss than a bark w .22lr, but 12ga has far higher volume of gas to release.
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Re: Rules for making a 12ga silencer

Post by whiterussian1974 »

How are you going to use this? For bird hunting the ported barrel will work well because it keeps the weight lighter and closer to the Action.

For Deer hunting, the baffles well work better because you don't need the quick swing rate and they will be quieter. That's why SilCo makes the Salvo12.

You'd probably be best served by buying the Salvo12. You don't have the Engineering Experience to make a Safe Unit that won't explode. But go ahead and make the 1/8" holes 8-12 per inch for 12"s if you wish. Just use quality Gr5 Ti, 304SS, or 6061-T6 Al (w the Al being twice as thick for an OD of 2.25" instead of 2.125".)
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