Materials Selection question

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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airsix
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Materials Selection question

Post by airsix » Mon Dec 16, 2013 2:49 pm

Hello! Great forum. It's been great digging through all the posts here learning what I can.

While I sit waiting for the return of the Form 1 for my first NFA project I had some questions about materials I'm hoping you'll educate me about.

I will be building a .30cal can for an AR pistol (with a Sig brace, so... you know...) chambered in 300 aac blackout. I'd like to turn K baffles on my lathe. If I turn them from aluminum and anodize them, can I expect decent life from them if I include a good blast shield at the base of the stack?

Summary: Is aluminum an acceptable material for K baffles? (SS would exceed the limits of my little lathe)

Follow-up: Is 6al/4va titanium an acceptable material for a blast shield? (I have some 0.100" plate sitting here on the shelf)

Thanks!

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Re: Materials Selection question

Post by Capt. Link. » Mon Dec 16, 2013 3:30 pm

airsix wrote:Hello! Great forum. It's been great digging through all the posts here learning what I can.

While I sit waiting for the return of the Form 1 for my first NFA project I had some questions about materials I'm hoping you'll educate me about.

I will be building a .30cal can for an AR pistol (with a Sig brace, so... you know...) chambered in 300 aac blackout. I'd like to turn K baffles on my lathe. If I turn them from aluminum and anodize them, can I expect decent life from them if I include a good blast shield at the base of the stack?

Summary: Is aluminum an acceptable material for K baffles? (SS would exceed the limits of my little lathe)

Follow-up: Is 6al/4va titanium an acceptable material for a blast shield? (I have some 0.100" plate sitting here on the shelf)

Thanks!
Try 416 SS or 303 with a pistol length barrel.You will be able to cut it with HSS tools on a small lathe.The erosion due to gas cutting may be excessive with aluminum in centerfire in your application.The cutting of Ti will be impossible on a small lathe and SS a better choice for a blast baffle.
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Re: Materials Selection question

Post by 57fairlane » Mon Dec 16, 2013 6:08 pm

If you are going to do subs only, I'd go with a nice 303/304 blast baffle and you could get by with 7075 baffles after provided you have enough thickness per whatever diameter you are going to go with.

To stand up for awhile under supersonic rounds, you'll have to make the aluminum baffles pretty thick depending on your barrel length.

At a minimum do a stainless blast baffle.

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Re: Materials Selection question

Post by Fulmen » Mon Dec 16, 2013 6:37 pm

While the 300 isn't the worst round out there aluminum will erode to some extent. If you want a can that lasts (almost) forever it's not the best choice. Also, the 300 is an extremely "wet" round. In my bolt gun I never shoot fast enough to get the can hot, so it accumulates condensation. If I don't dry it out it will corrode badly within days.

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Re: Materials Selection question

Post by CMV » Mon Dec 16, 2013 8:20 pm

Go with CPT Link's advice on the 416. Much more durable, not overly expensive, and easy to machine. One of the easiest stainless steels to work with. Less worries vs AL in the long run.

BUT for subs only, I wouldn't be surprised if you got very long life out of 7075 K's. My 300 BLK subs are really mild. Dirty as all get out, but mild.
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Re: Materials Selection question

Post by airsix » Mon Dec 16, 2013 8:51 pm

My little mini-lathe just can't handle steel very well at all unless very small diameter. If aluminum is a poor choice I'd probably be better off press-forming freeze plugs. :(

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Re: Materials Selection question

Post by Dr.K » Mon Dec 16, 2013 9:01 pm

airsix wrote:My little mini-lathe just can't handle steel very well at all unless very small diameter. If aluminum is a poor choice I'd probably be better off press-forming freeze plugs. :(
There is always another way! For example, I sat on my first form1 for SIX YEARS! until I was in the position to buy a proper machine for the job. I had other silencers, but don't skimp out.

You only get one shot at this, and you have some time, try and do it right!

Ask around, someone somewhere close to you might have a machine that they would let you use maybe. I have some contacts like that, if you have a machine, then you know the basics. That would go a long way for me if someone wanted to use mine, and I trusted them of course.

Just don't skimp or lose hope yet, you don't even have the stamp yet! Ask around.

BTW, where do you live? Might be one of us right down the road.
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Re: Materials Selection question

Post by whiterussian1974 » Tue Dec 17, 2013 1:20 am

Dr.K wrote:You only get one shot at this, and you have some time, try and do it right!
Wise words as usual my friend.
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Re: Materials Selection question

Post by airsix » Tue Dec 17, 2013 3:31 pm

Thanks guys!

To keep the discussion going...

I do intend to shoot subs almost exclusively. If I stuck to subs and used a good stainless blast baffle, what would you expect the round-count life of 7075 K-baffles to be (type-2 anodized). I thought I had read that some of the commercial cans are using non-anodized aluminum K-baffles. In addition to ease of machining aluminum would be significantly lighter which is the other reason I'm drawn to it.

I'm sure I'm over-complicating things, but the thread about titanium valve-spring-retainers had me wondering about designing an aluminum K-baffle with a titanium or stainless port face/sleeve for durability. Still thinking about how you'd stake/retain such a thing to keep it together despite dissimilar thermal expansion of the materials. Wouldn't it be great though, if you could turn out light aluminum K's and face their ports with a steel washer or such that was resistant to erosion?

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Re: Materials Selection question

Post by Bendersquint » Tue Dec 17, 2013 6:49 pm

airsix wrote:Thanks guys!

To keep the discussion going...

I do intend to shoot subs almost exclusively. If I stuck to subs and used a good stainless blast baffle, what would you expect the round-count life of 7075 K-baffles to be (type-2 anodized). I thought I had read that some of the commercial cans are using non-anodized aluminum K-baffles. In addition to ease of machining aluminum would be significantly lighter which is the other reason I'm drawn to it.

I'm sure I'm over-complicating things, but the thread about titanium valve-spring-retainers had me wondering about designing an aluminum K-baffle with a titanium or stainless port face/sleeve for durability. Still thinking about how you'd stake/retain such a thing to keep it together despite dissimilar thermal expansion of the materials. Wouldn't it be great though, if you could turn out light aluminum K's and face their ports with a steel washer or such that was resistant to erosion?
Why not have the baffles Type3HC anodized, the baffles will last longer?

Length of barrel, rate of fire, powder used will determine the lifespan.

Gemtech doesn't anodize their baffles and their baffles lifespan suffer because of it. Every Type3HC anodizing run we do has at least 2 or 3 Gemtech baffle stacks in it.

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Re: Materials Selection question

Post by whiterussian1974 » Tue Dec 17, 2013 7:51 pm

Bender is right about Type 3.
I'm shocked that GemTech doesn't Type 3. Even MagLite does and that's just a flashlight tube!
Your thought about a cupped 304SS washer in front of Al K-baffles sounds good. As long as you keep the bore lip to scoop gas outward, just sandwich them together in a stack and don't worry about thermal rates. The clipped hole would rotate though, and you might just want to except it. Maybe place 2 or 3 opposing scalops to create turbulance.
Have you considered just sandwiching Flat and Cone washers together and drilling bleeder holes.
Image
Here is a commercial variant. http://www.rwsgunsmithing.com/catalog/x ... -silencer/ Obviously theirs is machined, but proves the theory has merit.
Here is a version w only 4!! baffles. http://www.sbdgear.com/ProductDetails.a ... is%2DMicro
They claim 116dB for 7 baffles w CCI Standard Velocity. 117.5dB for 4 baffles.
Here's an eval.
http://www.youtube.com/watch?v=cTXNn7Mu5-M ·1 min · 1,197 views · Added Aug 20, 2011
XCaliber Genesis Walther P22=114.9dB; XCaliber Genesis Micro Walther P22=117dB; XCaliber Genesis Ruger 10/22=116.3dB; These are the quietest silencers ...
Here is their Thread on this site. viewtopic.php?f=133&t=76160
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Re: Materials Selection question

Post by airsix » Tue Dec 17, 2013 8:06 pm

TypeIII would be great, but in my garage I can only do TypeII. But I do it well. :D

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Re: Materials Selection question

Post by Bendersquint » Tue Dec 17, 2013 9:15 pm

airsix wrote:TypeIII would be great, but in my garage I can only do TypeII. But I do it well. :D
Doesn't mean you can't send it out to be anodized.

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Re: Materials Selection question

Post by airsix » Wed Dec 18, 2013 1:38 pm

Bendersquint wrote:
airsix wrote:TypeIII would be great, but in my garage I can only do TypeII. But I do it well. :D
Doesn't mean you can't send it out to be anodized.

Now where's the fun in that? :D

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Re: Materials Selection question

Post by Bendersquint » Wed Dec 18, 2013 2:08 pm

airsix wrote:
Bendersquint wrote:
airsix wrote:TypeIII would be great, but in my garage I can only do TypeII. But I do it well. :D
Doesn't mean you can't send it out to be anodized.

Now where's the fun in that? :D
Sometimes function over fun takes the cake.

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Re: Materials Selection question

Post by ber778 » Wed Dec 18, 2013 3:55 pm

Do you have a recommended place that a form 1 builder can send baffles to be anodized?

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Re: Materials Selection question

Post by Bendersquint » Wed Dec 18, 2013 4:15 pm

ber778 wrote:Do you have a recommended place that a form 1 builder can send baffles to be anodized?
Only a licensed manufacturer can anodize your baffles for you.

We can anodize them for you, since we fit that bill.

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Re: Materials Selection question

Post by Historian » Wed Dec 18, 2013 5:04 pm

Bendersquint wrote:
ber778 wrote:Do you have a recommended place that a form 1 builder can send baffles to be anodized?
Only a licensed manufacturer can anodize your baffles for you.

We can anodize them for you, since we fit that bill.
Mr. B., can the 'home brew' 12V car battery, etc., anodizing kit be used
on individual baffles to make an impervious skin, or is the professional
process necessary for deep and long term wear.

40 years ago my friend was sending out a batch of Aluminum parts for
anodizing and let me give him my glass and glassless carriers for my 4 x 5
Omega D2V-XL enlarger. When I got them back I was delighted at the harness
of the surface and the perceptible reduction in light scattering and increase
in image quality.

Having been brought scratching into the 21st century with 25 M-Pixel cameras and
color printers with Photo Shop, etc., they now have a hallowed place on my darkroom
wall, gathering dust like the Dead Sea Scrolls.

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Re: Materials Selection question

Post by Bendersquint » Wed Dec 18, 2013 5:09 pm

Historian wrote:Mr. B., can the 'home brew' 12V car battery, etc., anodizing kit be used
on individual baffles to make an impervious skin, or is the professional
process necessary for deep and long term wear.

40 years ago my friend was sending out a batch of Aluminum parts for
anodizing and let me give him my glass and glassless carriers for my 4 x 5
Omega D2V-XL enlarger. When I got them back I was delighted at the harness
of the surface and the perceptible reduction in light scattering and increase
in image quality.

Having been brought scratching into the 21st century with 25 M-Pixel cameras and
color printers with Photo Shop, etc., they now have a hallowed place on my darkroom
wall, gathering dust like the Dead Sea Scrolls.
Home DIY anodizing can give you at best a Type2 finish.

Basically Type3 requires more specialized equipment and stricter controls of the entire process, it also penetrates deeper and is stronger.

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Re: Materials Selection question

Post by 57fairlane » Wed Dec 18, 2013 5:21 pm

ber778 wrote:Do you have a recommended place that a form 1 builder can send baffles to be anodized?
Call around. I think only SilencerCo does anodizing in house.

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Re: Materials Selection question

Post by Bendersquint » Wed Dec 18, 2013 5:43 pm

57fairlane wrote:
ber778 wrote:Do you have a recommended place that a form 1 builder can send baffles to be anodized?
Call around. I think only SilencerCo does anodizing in house.
Silencerco does anodize their own parts but will not anodize parts for anyone else. They don't provide services, just silencers.

What most don't realize is that most manufacturers don't produce their parts in house they sub them out and that mfg anodizes the parts on site.

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Re: Materials Selection question

Post by CMV » Wed Dec 18, 2013 8:56 pm

How does that work for a form-1 builder? If someone were to send you (or any manufacturer) form-1 parts for finishing services, repair, etc, what's the process? Send the whole thing? You do the work and send it directly back? Or do you have to send it to a class 3 dealer & the customer gets it from them? Does it matter if the 2 parties are in the same state or not?

I'm sure you told me this once, but I've since cleaned out my PMs & have the memory of a fruit fly at times. I'm sure others would like to know too.

How much work could you do via the 'send it out' process? Could I theoretically send you a tube & foot of uncut barstock & get completed parts back? Extreme example, but where's the cutoff of what could be farmed out where the form-1 holder isn't present?
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Re: Materials Selection question

Post by Bendersquint » Wed Dec 18, 2013 9:07 pm

CMV wrote:How does that work for a form-1 builder? If someone were to send you (or any manufacturer) form-1 parts for finishing services, repair, etc, what's the process? Send the whole thing? You do the work and send it directly back? Or do you have to send it to a class 3 dealer & the customer gets it from them? Does it matter if the 2 parties are in the same state or not?

I'm sure you told me this once, but I've since cleaned out my PMs & have the memory of a fruit fly at times. I'm sure others would like to know too.

How much work could you do via the 'send it out' process? Could I theoretically send you a tube & foot of uncut barstock & get completed parts back? Extreme example, but where's the cutoff of what could be farmed out where the form-1 holder isn't present?
You have to send the complete can in for whatever service you are wanting. You can send a silencer part to a mfg, but a mfg can't send a silencer part back. Complete can in, complete can out.

Yes, it is returned back to its owner.

As a mfg i can accept and service anything NFA, from any state.

Its limited what can be done via the send out process. Alot of it can be grey area so its based on how grey the 07/02 you are subcontracting the work is willing to go. Most 07/02's don't want to deal with it and I can't blame them, which is why we are very very selective on what we will fab for a Form1 build and focus on finishing the parts whether it be anodizing or melonite etc...

No you can't send out a tube and barstock and say send me back a silencer.....that would make the 07/02 the maker, not you the Form1 holder.

If the Form1 holder is not present the only one that can do the work is an 07/02.

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Re: Materials Selection question

Post by Baffled » Thu Dec 19, 2013 12:18 pm

Some tricks for turning stainless steel on a light, low-powered machine.

First, get rid of any brazed carbide tools. On a fractional HP machine, they will suck at turning stainless.

Work on grinding some HSS tools (cobalt is good) that have the following attributes:

- A rake similar to what you'd see for aluminum. Positive rake decreases cutting pressures dramatically. The drawback is that they can and do dig in if care is not taken.

- A tiny tip radius. In other words, it's a sharp, pointy little bugger. Picture a thread form tool with the tip slightly rounded, but not much

- Set the machine up for fine feed, and tighten the gibs down.

The tool should look a bit like this:

Image

Image

A setup like this can shave 0.0003" on a pass without skip or rub, if the lathe is accurate and tightened down. If the cutter isn't continuously making swarf, it's rubbing, and probably dulling AND work hardening the material. You want a continuous cut.

I'm sure 416 is good stuff, but I've always liked 303. Remember the ditty - "303, she's for me. 304, she's a whore."

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Re: Materials Selection question

Post by whiterussian1974 » Thu Dec 19, 2013 12:35 pm

Bendersquint wrote:What most don't realize is that most manufacturers don't produce their parts in house they sub them out and that mfg anodizes the parts on site.
Wouldn't the subcontractors also have to be FF7/SOT? After all, they are working Suppressor parts.
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