Silencer for 9mm Carbine

[Langfinger]

I've been researching and trying to understand how silencers work and how they are built for the last few weeks. I now want to build my own silencer for a 9mm Luger (single shot, break action) with 12" barrel length. Projectiles are mostly 115gr. subsonic
Here are the specs I came up with:

-8" length, 1.6" diameter tube (7075 aluminium or titanium)
-K Baffles with 60° cone angle (7075 aluminum; blast baffle made out of 17-4 stainless steel)
-a smaller tube to support the blast chamber (7075 aluminium)
-M13,5 LH thread for barrel attachment (or maybe 1/2-28 1/2-36?)
-endcaps are threaded, not welded
-exit hole diameter is 0.4"

Please let me know what you think about these specs so far.
I still have some questions left like:
-do I get any advantage of a muzzle brake/flash hider inside the blast chamber?
-how big does the blast chamber has to be?
-how many K baffles do I need?
-what is the best K baffle design to begin with?
-does the closed action have any influence on blast chamber pressure (since the shell is not ejected, so no gases can escape through the chamber end of the barrel)
-why are most MP5 and UZI supressors so big, compared to the pistol silencers? - Isn't muzzle pressure smaller, the longer the barrel is?
-am I missing something?

Thank you very much for your time and help. I really appreciate it. I will participate in this forum, as soon as I know what I'm talking about.

[propeine]

I've been researching and trying to understand how silencers work and how they are built for the last few weeks. I now want to build my own silencer for a 9mm Luger (single shot, break action) with 12" barrel length. Projectiles are mostly 115gr. subsonic
Here are the specs I came up with:

-8" length, 1.6" diameter tube (7075 aluminium or titanium)
-K Baffles with 60° cone angle (7075 aluminum; blast baffle made out of 17-4 stainless steel)
-a smaller tube to support the blast chamber (7075 aluminium)
-M13,5 LH thread for barrel attachment (or maybe 1/2-28 1/2-36?)
-endcaps are threaded, not welded
-exit hole diameter is 0.4"

Please let me know what you think about these specs so far.
I still have some questions left like:
-do I get any advantage of a muzzle brake/flash hider inside the blast chamber?
-how big does the blast chamber has to be?
-how many K baffles do I need?
-what is the best K baffle design to begin with?
-does the closed action have any influence on blast chamber pressure (since the shell is not ejected, so no gases can escape through the chamber end of the barrel)
-why are most MP5 and UZI supressors so big, compared to the pistol silencers? - Isn't muzzle pressure smaller, the longer the barrel is?
-am I missing something?

Thank you very much for your time and help. I really appreciate it. I will participate in this forum, as soon as I know what I'm talking about.

-I think 1.6 is larger than it needs to be and 1.375 would be damn close in suppression level, lighter and cheaper. Diminishing returns and all that.
-I like my 8" 9mm suppressor
-I don't like metric threads because my lathe can't cut them plus you may find other guns that use 1/2-28 in 9mm personal choice
-Bore diameter of .4 works for me

-I run a brake on my carbine and a booster on my pistol. No clue if there is an advantage but it takes wear off the blast baffle
-Mine is about 1" maybe 1.25" I'd have to measure
-I have 7 and the last one fits inside the end cap
-Sometimes argued but 60° is still common with parallel ball mill ports
-Even if it did most everyone does pressure calcs with muzzle pressure which wouldn't take that into account
-Full auto causes increased pressures/longer duration due to stacking plus there isn't as much weight concern as there is with pistol silencers

Only thing you're missing in my opinion is that aluminum can't be cleaned as easily as Ti. No ultrasonic, no "dip". Up until the HPA passes I would not personally have an aluminum silencer.

[Langfinger]

Thank you propeine for sharing your thoughts and knowledge. That already helped me a lot.
I will include a muzzle brake then. Tube and endcaps will be made from titanium.
Did you also make the baffles out of titanium?

[propeine]

Thank you propeine for sharing your thoughts and knowledge. That already helped me a lot.
I will include a muzzle brake then. Tube and endcaps will be made from titanium.
Did you also make the baffles out of titanium?

Yup I sure did. No aluminum in any of my cans. 17-4 blast baffle in my 308 suppressor though. I shoot cast lead too though so cleaning is maybe more important to me than to you.

[fishman]

Uzi, mp5, and other subgun cans are big compared to 9mm pistol cans because pistol cans have to be small and light to operate and not obstruct sight picture. 1.6" is a good diameter unless you're trying to minimise weight.

[Capt. Link.]

Submachine gun suppressors are large mostly because of gas volume.Most pistol suppressors will never see the heat or the pounding a subgun can impart upon a can.One advantage these old suppressors is they can be very quiet even with heavy loads.This is a favorite of mine that is perfect for a stealthy carbine.
MK-9

[yondering]

+1 to everything propeine said, except that other than cleaning, there's no real need to use anything but aluminum for the suppressor you describe. Personally I haven't found enough fouling to matter much in my 9mm cans but that's a personal preference that some find more important than others. For durability, 7075 aluminum will work fine for everything if that's what you want to use, although steel or Ti barrel threads would be a good idea..

[propeine]

+1 to everything propeine said, except that other than cleaning, there's no real need to use anything but aluminum for the suppressor you describe. Personally I haven't found enough fouling to matter much in my 9mm cans but that's a personal preference that some find more important than others. For durability, 7075 aluminum will work fine for everything if that's what you want to use, although steel or Ti barrel threads would be a good idea..

You shoot a lot of cast. I'm surprised to hear you say that honestly! Still yondering's word is worth a lot to me and capt Link has probably been at this since I was a twinkle in my dad's eye so his words are even more heavily weighted.

[Langfinger]

Thank you all for sharing your knowledge with me. I will settle for a 1.6" diameter titanium tube with titanium endcaps. The blast baffle will be stainless steel, the rest 7075 aluminium. I will also use a muzzle brake on which the silencer can be screwed on.
I'm currently designing a K baffle using a CAD program. I will post a picture of the design when it's finished. Becuase of the bigger diameter I will only be able to use 6 baffles.

[fishman]

Becuase of the bigger diameter I will only be able to use 6 baffles.

My 1.625" can has k baffles only a inch long, you should be able to fit 7 Ks

Edit: I forgot about the brake. 6 plus a brake makes sense

[Langfinger]

Ok, so this is the current status of my K baffle design.
Overall diameter is 1.45". Cone angle ist 60°.
Diameter of endball mill for scoop and mouse hole is .375"

What do you think of the allignment of the plate port and the coaxial port?

[T-Rex]

For reference, these are 30cal K's which fit inside a 1.375" x .065" tube.



They stack inside on another, to keep the interior of the tube clean.
5 of these do an amazing job at suppressing SS 30cal projectiles.

[fishman]

Ok, so this is the current status of my K baffle design.
Overall diameter is 1.45". Cone angle ist 60°.
Diameter of endball mill for scoop and mouse hole is .375"

What do you think of the allignment of the plate port and the coaxial port?

Why bother with having the baffles nest into each other like you have shown?
Also, the half circle groove cut into the rear face of the baffles could be bigger

[yondering]

You shoot a lot of cast. I'm surprised to hear you say that honestly! Still yondering's word is worth a lot to me and capt Link has probably been at this since I was a twinkle in my dad's eye so his words are even more heavily weighted.

I do, especially 9mm, but it's all coated these days so the suppressor doesn't know there's lead in there. All I see is powder fouling, and it the accumulation is pretty slow.

[John A.]

OK, looks like it's time to break out a picture of an old 9mm can I made back around 2006 (I don't remember and am not going to dig out my F1 to check the date). It's been a long time, that's the only point I'm trying to make.

And it is a sealed can.

Anyway, the OD of the tube is 1.5", ID was around 1.370 ish.

Blast baffle was made from a steel engine valve retainer, all other baffles were made from titanium valve retainers.

This was done at a time when there wasn't even a whole lot of information on the internet, and even fewer people making their own.

It pre-dates a lot of common baffle designs today, and I must admit, it does a really good job, although it's a lot heavier than more modern cans.

I have fired 223, 7.62x39, 6.8 spc, ton of 22lr , 9mm (semi and full auto), 38 special, 357 mag, 300 blackout subs and supers. And probably others that I'm not thinking about.

Here is a photo that I took after I bought one of those little cameras from ebay to inspect the insides to make sure there are no cracks and nothing funny going on in there.

There doesn't seem to be hardly any leading at all. Maybe because I had used to for a long time and perhaps the fouling had already built up a protective layer against any lead mist to prevent it from sticking.

But regardless, this can has seen a lot of action over the years.

It's fouled, but it's fine.

Here is a photo before I tig welded it shut.



And after untold thousands of rounds of everything I have put through it.

[crazyelece]

I've been researching and trying to understand how silencers work and how they are built for the last few weeks. I now want to build my own silencer for a 9mm Luger (single shot, break action) with 12" barrel length. Projectiles are mostly 115gr. subsonic
Here are the specs I came up with:

-8" length, 1.6" diameter tube (7075 aluminium or titanium)
-K Baffles with 60° cone angle (7075 aluminum; blast baffle made out of 17-4 stainless steel)
-a smaller tube to support the blast chamber (7075 aluminium)
-M13,5 LH thread for barrel attachment (or maybe 1/2-28 1/2-36?)
-endcaps are threaded, not welded
-exit hole diameter is 0.4"

Please let me know what you think about these specs so far.
I still have some questions left like:
-do I get any advantage of a muzzle brake/flash hider inside the blast chamber?
-how big does the blast chamber has to be?
-how many K baffles do I need?
-what is the best K baffle design to begin with?
-does the closed action have any influence on blast chamber pressure (since the shell is not ejected, so no gases can escape through the chamber end of the barrel)
-why are most MP5 and UZI supressors so big, compared to the pistol silencers? - Isn't muzzle pressure smaller, the longer the barrel is?
-am I missing something?

Thank you very much for your time and help. I really appreciate it. I will participate in this forum, as soon as I know what I'm talking about.

My $0.02 FWIW

I like aluminum for 9mm - but I reload. I use a fast burning clean powder and a full jacketed bullet. I only see powder fouling and it aids in suppression. I have over 5000 rounds through my old multimount and it is still going strong.

With a low pressure round like 9mm, K baffles are great. A blast chamber isn't really needed with the low pressure rounds and I like the muzzle sitting about 0.25" away from the blast baffle.

Again I reload, the powder I use is completely burnt before it gets out the barrel so I don't worry about baffle errosion, therefore I don't worry about a muzzle brake either. My cans are setup for tri-lug or 1/2x28. I don't have a foreign host as of yet so I don't have a metric setup. In my case I would try to cut off metric threads and rethread 1/2x28 if possible as my lathe can't cut metric. If I had to have metric I'd have to farm it out or use an over the counter adapter.

I would shoot for 1.3x6 or whatever I could find around that diameter and let the baffle design determine length. Again, this is also for my situation where my lathe through bore is 1.5" so I wouldn't need to use a steady rest.

Closed action doesn't effect blast pressure per say (as the action shouldn't be opening during the high pressure or you'd have case seperation) but it does help to not get backpressure and port noise. A closed action 9mm subsonic should be damn near hollywood quiet through an effective suppressor.

MP5, Uzi, and other subgun cans are large because they were designed specifically for those weapons. Not only are they auto loaders but they are fullauto. The backpressure, and rate of fire of the host requires a large volume for the gasses to properly bleed off and expand without heating the material to the point of metal fatigue and failure.

One other thing to consider is you mentioned welding. If you have the ability and tooling to weld aluminum then you should be set. If it were me, I would thread the endcaps and glue them to the tube with red locktite. But again I have a lathe. My only welder is mig and it's setup to weld with flux core for steel.

All-in-all, I think your on the right track, and that thing should be a nice quiet shooter when completed.