Building my first can FORM 1 !!!

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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METALMAN
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Building my first can FORM 1 !!!

Post by METALMAN » Wed Sep 24, 2008 2:43 pm

I have a few questions. I will be building a monolithic style supressor. I want the internal monolithic core in aluminum, and the sleeve out of stainless or mild steel (are there advantages outside of corrosion resistance?). It will be built for my UZI so I will be incorporating the barrel nut into the end of the can.

1. I have read that there is sometimes (always?) a gap between the core and the sleeve? Is this true? And if so, how much of a gap do I need?

2. I have seen some cans with small holes in the ends of the can. What are these for? And are they necessary? How large do they need to be? How do determine their size? (this can will be for 9mm)

3. When you make a can, once the FORM 1 is approved , I assume you have to etch of stamp your name , city , and state into the can to fulfill the ATF's requirements.

4. How much larger than the diameter of the bullet does the exit hole have to be? Since I am shooting 9mm

5. My UZI has been SBR'ed so the barrel is about 3" long, how far can the barrel extend into the can? Should it just meet where all the gas chambers begin?



I am sure I will have several more questions...

Thanks for any input!
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lawless
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Re: Building my first can FORM 1 !!!

Post by lawless » Wed Sep 24, 2008 3:53 pm

METALMAN wrote:I have a few questions. I will be building a monolithic style supressor. I want the internal monolithic core in aluminum, and the sleeve out of stainless or mild steel (are there advantages outside of corrosion resistance?). It will be built for my UZI so I will be incorporating the barrel nut into the end of the can.

1. I have read that there is sometimes (always?) a gap between the core and the sleeve? Is this true? And if so, how much of a gap do I need?

2. I have seen some cans with small holes in the ends of the can. What are these for? And are they necessary? How large do they need to be? How do determine their size? (this can will be for 9mm)

3. When you make a can, once the FORM 1 is approved , I assume you have to etch of stamp your name , city , and state into the can to fulfill the ATF's requirements.

4. How much larger than the diameter of the bullet does the exit hole have to be? Since I am shooting 9mm

5. My UZI has been SBR'ed so the barrel is about 3" long, how far can the barrel extend into the can? Should it just meet where all the gas chambers begin?



I am sure I will have several more questions...

Thanks for any input!
1. There has to be a small gap or youll never get it apart. Unless this will pull double duty on a 22 id just seal it and go with an easier design.

2.If youre referring to the one that is built by soundtech,its one of the loudest cans youll ever hear. Forget that stupid hole nonsense.

3. You need a serial# too.

4. Ill let someone else answer that as I dont remember the exact numbers.

5. It can extend in as far as you want really. As long as it is incorporated
into the design then go for it.

Also make the whole thing thin stainless. If youre going for easier machining on the core then....ok. A stainless blast baffle is a must for any SBR if you ask me. Id make t whole thing out of steel so your thermal propertiesof the metal youre using remain constant. Or youre never gonna get that sleeve off of an aluminum core.
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jandbj
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Re: Building my first can FORM 1 !!!

Post by jandbj » Thu Sep 25, 2008 10:15 am

METALMAN wrote:2. I have seen some cans with small holes in the ends of the can. What are these for? And are they necessary? How large do they need to be? How do determine their size? (this can will be for 9mm)
Are you referring to the holes for disassembling the endcaps from the tube, like on a TAC 65?

Image


RE: the monolithic stack, I think the simple one made by HotGuns on here with perhaps some added holes 90 degrees off from the original design is the best compromise between strength of the stack and ease of machinability.

Image

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John A.
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Re: Building my first can FORM 1 !!!

Post by John A. » Tue Sep 30, 2008 5:55 pm

My replies in Red, but keep in mind, I'm far from being an expert of anything, but I'll try to answer what I can.
METALMAN wrote:I have a few questions. I will be building a monolithic style supressor. I want the internal monolithic core in aluminum, and the sleeve out of stainless or mild steel (are there advantages outside of corrosion resistance?). It will be built for my UZI so I will be incorporating the barrel nut into the end of the can.

Trying to answer your question about corrosion, Various steels' rust. Even the Stainless steel ones. Aluminum doesn't. At least not in the same way steel does.

Al is also a softer metal and easier to overheat (melt). And not to mention a lot lighter too. I personally think Titanium is a better choice compared to Al.

Though there are a lot of Al suppressors out there and I'm sure I could be tarred and feathered for mentioning it.

If you're asking about galvanic corrosion between using 2 different metals, I'm not the guy to answer that one. Hell, I may not have even used the correct terminology :lol:


1. I have read that there is sometimes (always?) a gap between the core and the sleeve? Is this true? And if so, how much of a gap do I need?

My suppressor has .001 gap between the spacer and the outer tube and if it's not gunked up, is easy to slide them in and take them out. But mine is welded shut too because I'll also be shooting rifle calibers out of it. I don't know how easy they would be to remove if they were gunked up. I wanted the least amount of gap as I could get since I'm using flat baffles (valve retainers) to avoid misalignment.

If you're making a monocore, just thread the core and use it as the part that screws onto the barrel, so you don't have to worry about misalignment unless you melt it down, but with the 3 inches of space between the barrel nut and the muzzle, I'd have to think about how to make one like that.


2. I have seen some cans with small holes in the ends of the can. What are these for? And are they necessary? How large do they need to be? How do determine their size? (this can will be for 9mm)

See the answer above--probably for disassembling if you make threaded caps. The size of the holes are determined by the tool you're going to make or use to twist them on and off with. But you don't have to drill all the way through the caps. Just deep enough to get the tool seated is all.

3. When you make a can, once the FORM 1 is approved , I assume you have to etch of stamp your name , city , and state into the can to fulfill the ATF's requirements.

Yep, it has to be engraved to meet the fed requirements.

4. How much larger than the diameter of the bullet does the exit hole have to be? Since I am shooting 9mm

There's a thread on here somewhere about bore sizes. You could make it as big or as little as you want depending on your machining abilities and equipment. The bigger the bore, the less likely to get a baffle strike.

5. My UZI has been SBR'ed so the barrel is about 3" long, how far can the barrel extend into the can?

As far as you want it to. If you're going to have a dedicated suppressor for it, you could drill ports in the barrel and use the expansion chamber as a reflex type suppressor quiet well. Kind of like the old Cobray/Mac suppressors

Should it just meet where all the gas chambers begin?

I'm not sure what you're asking here.

I am sure I will have several more questions...

Thanks for any input!

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METALMAN
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Post by METALMAN » Tue Sep 30, 2008 7:55 pm

I guess the real question about bore size is;

Is a tighter bore size going to direct more energy behind it into the chambers thus silencing even more, or does bore size matter? If I could get away with +.065" larger than the 9mm round I would be happy! But i don't want to build an inneffective supressor!
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John A.
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Post by John A. » Tue Sep 30, 2008 9:17 pm

I don't think the bullet is going to redirect the energy away behind it as much as it is, the hole being more narrow just won't let the gas go straight through (out) as easy.

When gas leaves the gun muzzle, it's going to expand into the chambers whether the bullet is there or not. (relatively speaking). And taking into consideration, the bullet isn't going to do much in the scheme of things to be able to do much with the gas pressure. That's what's pushing the bullet forward to begin with.

The job of the suppressor is to catch, cool, slow the expanding gas. and obstruct and cause as much turbulance in there as it can to achieve that effect.

The bigger the hole, the likely the louder it will be.

I'm hesitant to recommend bore sizes. If you want some specs of bore sizes that have worked in the past, here's a pretty good link. 9mm is listed. viewtopic.php?t=24664

And here's another link that helped me a lot when trying to decide which SAE drill bits to order.

http://mdmetric.com/tech/cvtcht.htm
I don't care what your chart says

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