Baffle Stack Advice

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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dma
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Baffle Stack Advice

Post by dma » Wed Jan 13, 2021 1:23 am

Working on building a can with the following parts and am looking for input on baffle orientation.

8.8" x 1.5" OD tube - grade 9 titanium
(3) 60deg baffles .75" skirt - heat treated 17-4 stainless
(8) radial baffles .5" skirt - heat treated 17-4 stainless

This will leave approximately 2" for the blast chamber once the end caps are on. The blast chamber will be lined with a stainless sleeve.

Will mainly be used on a 7.5" 300 Blackout and occasionally a 16" 5.56 AR and 19" 308 bolt gun. Subs and supers. All hosts have SDTA brakes or flash suppressors with external threads.

I have three possibilities roughly sketched out in no particular order. The curvature of the radial baffles are slightly exaggerated in the drawing (picture of radials below). My primary question is how you all would arrange the baffles for best all around performance on the hosts listed above.

Image

Radials:

Image

Thanks guys.

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whiterussian1974
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Re: Baffle Stack Advice

Post by whiterussian1974 » Wed Jan 13, 2021 3:42 pm

Just throwing this out there.

I'd say 1 or 2 cones at first, and then the remainder radials. It makes no sense to have cones at front AND rear. Cones perform better under high pressure supersonic conditions. It also parts the blast wave like on a ramjet inlet.

The radials are great, but the long "throat" might create boundary layer conditions if there isn't enough clearance, and I'm not certain how deep into the preceding neck each mouth intrudes. This might create a situation where the gasses more effectively enter, then dwell for longer. Great conditions for further down the stack.

I'll be eager to hear what others have to say about this. :)
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dma
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Re: Baffle Stack Advice

Post by dma » Wed Jan 13, 2021 3:48 pm

Made some changes based on feedback from the form1suppressor board. Changed the radials to super dupers and since this is a sort of hybrid can, I left the 60s. Now I just need to figure out if the 60s would perform better in the front or rear of the stack (or some front some rear).

This is the current drawing:

Image

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whiterussian1974
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Re: Baffle Stack Advice

Post by whiterussian1974 » Wed Jan 13, 2021 7:28 pm

Yes. That looks excellent. I imagine that the large volume at the end will be filled by the last endcap.
Consider forming a small cone at the mouth of the endcap's exit hole. Just a small 1/4" lip will work great. :wink:

The 1st is all that you need. The 2nd is a very fancy design.
Image
Image
The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
The Death of One is a Tragedy, a million only a statistic.-Stalin
Well I AM 1/16 Demon on my Father's Side!-Dresden Files

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Re: Baffle Stack Advice

Post by dma » Wed Jan 13, 2021 9:13 pm

The stack will get pushed in by the end cap and the balance on the BC end will be measured and sleeved with a titanium spacer. As far as the cone at the end cap, what's a good way of going about that? VSR sandwiched between skirt of last baffle and end cap? I ordered the SDTA blank end cap which I believe is flat on the rear. No access to a lathe at the moment unfortunately.

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Re: Baffle Stack Advice

Post by whiterussian1974 » Wed Jan 13, 2021 9:20 pm

Yes, VSR or even freeze plug. Anything that will form a lip to retain gas and create a 'choke point' before the gases can exhaust.
The heat and pressure near the Exit will be so low, that nearly any formable metal should be fine. Just not tin, lol :mrgreen:

You could even braze a collar on with Oxyacetylene torch. Anything that will adhere. Heck, I suppose that a strong JPWeld would even work for a long time. I used it on a tractor and it's still working fine.
The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
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Re: Baffle Stack Advice

Post by dma » Wed Jan 13, 2021 10:32 pm

Thanks, I'll look into a cone for the end cap once it gets here. Someone said SD updated their solid end caps but I can't find any recent pictures of one.

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Re: Baffle Stack Advice

Post by Capt. Link. » Thu Jan 14, 2021 12:03 am

A stainless blast chamber liner is not truly needed but if you need a spacer double butte the piece to keep it light.
https://images.app.goo.gl/QgKVcNtsdrkUgubMA

I would build for subsonic performance and maximum strength for the 30's. Cones are very strong so putting them up front would be good engineering. The use of frustoconical baffles nested together 10-12 with the cones should net low spl #. Clipping & porting the stack along with welding it would be a good idea for strength and suppression.

I'm not sure that the ported end cap is needed for a medium bore, those were designed to limit the uncorking sound of big bore suppressors. I have seen a product improved version , for those who are interested.
https://www.katom.com/229-152T.html?gcl ... gK7VvD_BwE

:D :D ( drill through the radial cap hole's)
https://i1300.photobucket.com/albums/ag ... da8478.png


whiterussian1974 ..its good to see you posting.

Boundary layer effects only occur when baffles are miss-bored to the bullets point of view. A radials decreasing constriction or a thin abrupt one that is centered should cause the least disruption to a projectiles stability.

I have never seen a kit piece are they solid or a stamping ? https://i.imgur.com/NF8u2Ax.jpg
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895

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whiterussian1974
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Re: Baffle Stack Advice

Post by whiterussian1974 » Thu Jan 14, 2021 12:51 am

Capt. Link. wrote:
Thu Jan 14, 2021 12:03 am
whiterussian1974 ..its good to see you posting.
Thank you my kind Brother. It's always nice to see you and Historian also. :)

I know that we can always depend upon your technical expertise and experience. And Historian always makes my day. Such great older uncles for me. Always a clever quip or great remembrance of something past.

I haven't seen DrK post in forever, I hope that he and his family are well.
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Well I AM 1/16 Demon on my Father's Side!-Dresden Files

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whiterussian1974
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Re: Baffle Stack Advice

Post by whiterussian1974 » Thu Jan 14, 2021 1:02 am

Capt. Link. wrote:
Thu Jan 14, 2021 12:03 am
I have never seen a kit piece are they solid or a stamping ?
Image
I think that they are solids that have been machined. But the Chinese aluminum ones are stamped.

I got a $20 kit 1"x6" for my .22 lr.

They are 0.03" stamped pieces. Very easy to drill through, but couldn't take a beating from a high power like .223".
Probably wouldn't last long on a centerfire pistol either. They would need a good blast baffle to take that fireball of partially combusted hydrocarbon pellets. :(
The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
The Death of One is a Tragedy, a million only a statistic.-Stalin
Well I AM 1/16 Demon on my Father's Side!-Dresden Files

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Re: Baffle Stack Advice

Post by dma » Thu Jan 14, 2021 12:19 pm

Capt. Link. wrote:
Thu Jan 14, 2021 12:03 am
The use of frustoconical baffles nested together 10-12 with the cones should net low spl #.
I was able to find a few patents mentioning this, but are there any good visual representations of this concept?
Capt. Link. wrote:
Thu Jan 14, 2021 12:03 am
I have never seen a kit piece are they solid or a stamping ? https://i.imgur.com/NF8u2Ax.jpg
My understanding is they are turned like their other cups. From PPA if I didn't mention it already.

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Re: Baffle Stack Advice

Post by Capt. Link. » Thu Jan 14, 2021 8:07 pm

dma wrote:
Thu Jan 14, 2021 12:19 pm
Capt. Link. wrote:
Thu Jan 14, 2021 12:03 am
The use of frustoconical baffles nested together 10-12 with the cones should net low spl #.
I was able to find a few patents mentioning this, but are there any good visual representations of this concept?
Radial = frustoconical
https://i.imgur.com/NF8u2Ax.jpg
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895

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Re: Baffle Stack Advice

Post by whiterussian1974 » Thu Jan 14, 2021 8:54 pm

Capt. Link: I think that it's your use of "nested" that's confusing him.

I think that you MEANT to say, "linearly sequential."
The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
The Death of One is a Tragedy, a million only a statistic.-Stalin
Well I AM 1/16 Demon on my Father's Side!-Dresden Files

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Re: Baffle Stack Advice

Post by Capt. Link. » Fri Jan 15, 2021 12:53 pm

whiterussian1974 wrote:
Thu Jan 14, 2021 8:54 pm
Capt. Link: I think that it's your use of "nested" that's confusing him.

I think that you MEANT to say, "linearly sequential."
"Close spaced"
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895

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