Form 1 design for 9mm PCC

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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quattro74
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Form 1 design for 9mm PCC

Post by quattro74 » Wed Sep 22, 2021 9:42 pm

Hey Everyone,

Newb here looking at designing a can for my AR9 pistol build. Was thinking of a 1.5 x 7 or 8" SDTA Ti Tube filled with radial SS cups. Direct thread 1/2 x 28 mount. A 1" spacer after reading on here to keep the blast chamber small for pistol calibers. Does it make a difference if I make the spacing between the first baffle/cone more than those subsequent? Should I also make the spacing on the final baffle to endcap(distal) larger? I want to run mainly subsonics through this can and I am concerned of building it too large, too many baffles for the subsonic ammo to clear and or the gun to cycle. My AR9 has a 8.3" barrel.

Thanks in advance

quattro74
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Re: Form 1 design for 9mm PCC

Post by quattro74 » Fri Sep 24, 2021 10:09 am

ok, So after further reading I'm thinking I want a more robust can than will handle the occasional mag dump. :)

Seems for 9mm the real decision is k-cups vs radials, then with the radials I should do progressive spacing and clipping ala Rusty? Bigger is better? I'm guessing since I have a 8.3" barrel there will be velocity for the 9mm sub ammo to get through the can without any strikes. I don't want an integral design. Where do people buy their k-cups these days in 1.354? Is that the correct size for the SDTA 1.36" tube?

Thanks

3strucking
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Re: Form 1 design for 9mm PCC

Post by 3strucking » Sat Sep 25, 2021 6:00 am

Turn them on a lathe.

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Capt. Link.
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Re: Form 1 design for 9mm PCC

Post by Capt. Link. » Mon Sep 27, 2021 3:16 pm

quattro74 wrote:
Fri Sep 24, 2021 10:09 am
ok, So after further reading I'm thinking I want a more robust can than will handle the occasional mag dump. :)

Seems for 9mm the real decision is k-cups vs radials, then with the radials I should do progressive spacing and clipping ala Rusty? Bigger is better? I'm guessing since I have a 8.3" barrel there will be velocity for the 9mm sub ammo to get through the can without any strikes. I don't want an integral design. Where do people buy their k-cups these days in 1.354? Is that the correct size for the SDTA 1.36" tube?

Thanks
Use a dozen ported frustoconical or 60*cones that are close spaced for subsonic use. Bumping the diameter to 1.5" would help also. While it is true that K baffles are superior your ability to make the port correctly using a off the shelf item is in question. Very few people know how so I'm not singling you out. No need to progressive space a 9mm.
The accuracy of machining is critical, I can't stress enough the importance of having a machinist assemble the suppressor to prevent a bullet strike.
-CL
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

quattro74
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Re: Form 1 design for 9mm PCC

Post by quattro74 » Mon Sep 27, 2021 4:12 pm

Thanks Capt,

I will probably have to buy parts from the suppliers as I don't have access to a local machinist. I do have a drill press, So I think I will be able to complete it. Like you say I don't feel comfortable with the K cups even though they do the best job. I think I can do the clipping more easily with the radial cones. Single clips or the Rusty style? Do I clip the blast baffle and the final baffle or not?

thanks.

Historian
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Re: Form 1 design for 9mm PCC

Post by Historian » Wed Sep 29, 2021 12:55 pm

The serious problem of aligning baffles was beautifully solved by Donald J. Walsh Junior
in his creative and unconventional patent* US5136923A. Central steel tube an extension of the firearm's
barrel the length of the suppressor screwed at end of barrel with outer ring
of and diameter end cap. Not too well known. Like the Rock & Roll disc jockeys
of the 50's would say "from the GROOVE-yard of forgotten tunes".

"'Those who do not learn history are doomed to repeat it." -George Santayana
Boston Latin School 1850's


Variations of this theme were to mill out a wide through slot along the length of the first
⅓ of the extension allowing the whole volume of the can to become an expansion
chamber. One of his implementations had an insertable perforated SS spool
between the extension and the can wall that created turbulence, disruption,
and decompression delays.

Saw/'heard' 2 implementations (cumbersome) long ago for .22 and 9mm.

Some can specs for .22:
O.D. 1.75";
length 8.5";
central spool half way between extension barrel
and can wall ... like a 'thin wall of toilet paper :) ;

Volume approximately 15± cubic inches ... three/four times that of the
present date commercial .. and desirable ... cans;

Machined extension I.D. diameter for .22 can was .28 to .30 inches.

For mental image picture an M3 Grease gun barrel** with trunnion.
Front end cap had just a hole for barrel to fit through. Back cap had threads
that 'trunnion' screwed into can shell.


In summary: one perfect alignment extension barrel, two end caps; and
if desired a perforated spool. No worry for hits. Four (4) parts!

As the estimable PTK once said on YouTube with his long K-baffle can on cut down Ruger "...that was not a BB gun you heard".

The 9mm similarly had a surprisingly low signature. H&K had a similar 'fat' can with baffles.

*<< https://patents.google.com/patent/US5136923A/en >>

** << https://indianapolisordnance.com/parts/ ... uct_id=135 >>

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