45 Cal Suppressor Design Review

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Colo32
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45 Cal Suppressor Design Review

Post by Colo32 » Mon Dec 31, 2018 7:32 pm

Hello, new member here. I own an array of suppressors and have always wanted to build my own. I have spent countless hours on this site absorbing as much as I can. I have been a machinist for over 30 years.
I have a CMMG Banshee in 45 ACP that I currently run a Hybrid 46 on. I want to make my own can just for this host. I want to go with K baffles on this. I'm struggling with the trade off of the skirt angle verses how many baffles I can get into a reasonable length. The housing will be 1.625 dia. titanium. I really don't want to get any longer than 9" long. I have gathered that in a given length, the more baffles the better. If there are no real downsides to going with a 45 degree skirt vs a 60 degree skirt, then that would obviously pack more baffles in a given length.
Please take a look at the cross jetting feature I have on the face. The back side is the common ball end mill cut, but on the front I have more of a ramp that I would profile with a ball end mill on my CNC.
I would appreciate any constructive criticism you guys have to offer.
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Re: 45 Cal Suppressor Design Review

Post by ECCO Machine » Mon Dec 31, 2018 10:45 pm

I've found cones and radial cones to work better for .45. That said, I have played with K baffles quite a bit, so here are my thoughts:

1: 90° cones (included, 45° compound angle) can absolutely be made to work, but as with any design, it's the sum of the parts, not a "magic bullet".

2: use more conventional quarter sphere scoops

3: trepan the rear. I've tried sectioning off the scoop section similarly to what you have illustrated, not great results.

4: radius at the waist instead of a square cut.

5: looks like the front face of one cone will butt against the rear face of the next, so lose the short skirt to get more baffles in.

6: put one or two cones before the Ks to deal with the higher pressure gasses.

This is the stack I run in my 2nd generation Phoenix 9, a 1.25x8" 9mm can. With good subsonic loads, it's barely louder than suppressed .22 pistols

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For the record, my Phoenix XLV-M, my current .45 offering, is 1.375x7" plus a 2" module. In full configuration, it has 14 cone baffles.
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Re: 45 Cal Suppressor Design Review

Post by Colo32 » Tue Jan 01, 2019 1:28 am

ECCO, thanks for the input. That's just the kind of things I am looking for. I want to have a good shot at getting this right the first time. Sounds like I should have just stuck to the tried and true features I've seen repeated here. I figured there would be a better way to start the cross flow with some geometry easier created on CNC equipment. The ball end mill in the face seems like a simpler solution for the home hobbyist to achieve.
As far as the length goes, is there a point of diminishing returns that you have experienced with 45 ACP?

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Re: 45 Cal Suppressor Design Review

Post by ECCO Machine » Tue Jan 01, 2019 3:10 pm

Colo32 wrote: I figured there would be a better way to start the cross flow with some geometry easier created on CNC equipment. The ball end mill in the face seems like a simpler solution for the home hobbyist to achieve.
It is easier, but sometimes making things more complicated doesn't improve performance. I've tried some very intricate designs, up to and including machining impellers onto the tip of a cone to reduce first round pop, only to find that tweaking the geometry of a standard cone profile and playing with the clip was more effective. That's why you see the more acute angle with the double clip on the first cone in the image of my Phoenix guts.

One thing that seems to be overlooked in many of the baffle drawings I've seen is that the very high pressure, supersonic gasses present for a very short duration and following a projectile behave nothing like the lower pressure, lower velocity and more constant flows that aerodynamic flow modeling programs are designed for. You have some very interesting phenomena going on with propellant gasses behind the bullet inside a suppressor, many of which are not easily modeled or predicted, which is why suppressor design is more iterative and artistic than it is straight forward engineering.

In general, of course, the goal is to reduce flame propagation & laminar airflow as much as possible. But then there are cases where a balance must be struck, as with semi-autos, where excellent SPL reduction at the mil spec position really doesn't matter if you're far higher at the shooter's ear. Since your host is a blowback carbine, this is an important consideration. On the Banshee, I would wager shooter's ear numbers with most available .45 cal cans are over 140 dBA. Since you indicate that this will be a dedicated can for that host, I would focus on minimizing backpressure rather than maximizing muzzle end suppression.
Colo32 wrote: As far as the length goes, is there a point of diminishing returns that you have experienced with 45 ACP?
I really couldn't say. I've always worked up from the shortest & slimmest dimensions until I struck a good balance betwixt size & suppression, so I don't have any particularly large critters. The biggest diameter .45 cal can I have is my Vorticis, which is 1.5" x8", but it's a rather unconventional critter that was designed to reduce port noise on blowbacks more than chase mil spec position numbers, so it's got a relatively compact baffle stack with a large blast & coaxial chamber, and some other features that focus on minimizing backpressure.

.45 cal is always going to present challenges due to the large aperture, so volume is definitely your friend, and length is more effective than diameter within practical limitations.
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Re: 45 Cal Suppressor Design Review

Post by Colo32 » Tue Jan 01, 2019 5:13 pm

The thing the Banshee has going for it is its radial delay blowback system as opposed to direct blowback. It helps with port noise for sure. I have attached some more pictures with the revisions you have suggested. I think I got them mostly addressed. I included, because I couldn't resist, 2 other "non-typical" designs. I used a 7/16" dia ball for the face port and 1/2" dia ball for the one on the skirt.
Thanks again for your input and patience.
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Re: 45 Cal Suppressor Design Review

Post by fishman » Tue Jan 01, 2019 5:22 pm

1. INSTALL CMMGs ACTION TUNING KIT
This will help more than any tweaks to your baffles will. Get that action to open up as late as possible.

2. Please do an integral. An integrally silenced, radial delayed, CMMG 45ACP is a beautiful thing. Ask me how I know.

3. My one regret with my 300blk k baffle can is that I didnt make the k baffles nest into each other like this:
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4. K baffles are all about the scoop at the waist. I think you'll want more scoop. Disrupt airflow through the waist as much as possible with an asymetrical scoop. This is key. You can see the drawings in the link in my signature for my take on this. Mine work great, but as a hobbyist, I don't have any R&D into perfecting it.
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Re: 45 Cal Suppressor Design Review

Post by fishman » Tue Jan 01, 2019 5:25 pm

Do you have access to a CNC mill?
EDIT: nevermind. Answer in the original post
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Re: 45 Cal Suppressor Design Review

Post by Colo32 » Tue Jan 01, 2019 5:56 pm

I have a folding stock adapter from Law Tactical on my CMMG. I made my own 4 oz extension to replace Law Tacticals that weighs 2 oz. I then modified 2 different buffers, one for unsupressed and one for the supressor. I get maximum reliability this way and swapping buffers on a folder is stupid quick. This gun is softer shooting than ANY other pistol caliber AR I have had the chance to compare it to. I was considering doing this integral, but I have been of the mindset to maintain its compactness with the folding stock and 3 lug adapter on the barrel. If I were to go integral, is it necessary to drill ports in the barrel, or can it be more of a reflex only? I am open to this for sure. Hmmmmm
Is the nesting for easier removal/cleaning???
Last edited by Colo32 on Tue Jan 01, 2019 7:11 pm, edited 1 time in total.

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Re: 45 Cal Suppressor Design Review

Post by T-Rex » Tue Jan 01, 2019 7:07 pm

Personally, I think 1-5/8 is unnecessarily large. Not only does weight increase drastically, but your baffle cross section suffers. They'll require more length, per baffle, with a negligible return per cu in. Cones are great for the larger OD's because you can easily use a disc/shoulder style.

Your mount is also much larger than it needs to be. You'll want a minimal blast volume.

ECCO's recommendation of cones before K's is solid advice. Here's a 45acp K-Baffle design I did a couple years ago. The suppressor dimensions are roughly 1-3/8 x 9. This holds 2 cones and 8 K's.

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Also, K's are difficult enough to get perfect so I'd recommend sticking to one design.
Colo32 wrote:Is the nesting for easier removal/cleaning???
Yes.

Here's my version

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Re: 45 Cal Suppressor Design Review

Post by Colo32 » Tue Jan 01, 2019 7:44 pm

The initial reason for the 1.625 OD is to fill the inside of the 1.75 ID carbon fiber handguard that I have planned. I'm not stuck on that size, I just like the way it fills the handguard.

The mount is the size it is to accommodate the SilencerCo 3 lug adapter I'm currently using on the Hybrid 46. I will likely stick with this mounting system unless I completely change directions and go integral or reflex.

If I go with the nested K's, won't that be adding significantly more weight to the build? I realize the outer tube can now have a thinner wall, but it can't be much thinner and still allow for endcap threads. I suppose the spacer could be quite thin walled and/or a separate piece.
Much to think about, there is!

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Re: 45 Cal Suppressor Design Review

Post by John A. » Tue Jan 01, 2019 8:23 pm

Colo32 wrote:The initial reason for the 1.625 OD is to fill the inside of the 1.75 ID carbon fiber handguard that I have planned. I'm not stuck on that size, I just like the way it fills the handguard.

The mount is the size it is to accommodate the SilencerCo 3 lug adapter I'm currently using on the Hybrid 46. I will likely stick with this mounting system unless I completely change directions and go integral or reflex.

If I go with the nested K's, won't that be adding significantly more weight to the build? I realize the outer tube can now have a thinner wall, but it can't be much thinner and still allow for endcap threads. I suppose the spacer could be quite thin walled and/or a separate piece.
Much to think about, there is!
I too like my silencers to fit well inside of the handguards too. Though, most newer handguards are "slim" and smaller ID/OD than the older ones too, so it depends all what you're using it on.

The reason that integral suppressors work better than reflex (you can do both at the same time) but the reason that ported barrels work better is the burning propellant forces more of the pressure out of the bore of the silencer and into the area over the barrel. Being pressurized, will jet the gas out of the barrel.

This makes less gas that the silencer has to deal with initially when you pull the trigger and makes it more quiet, and also gets more gas away from the large bore of the can, which as you know on a 45acp is pretty large in the first place.

So, it is the most effective way to make the best sounding 45 can out there.

Having nested baffles make removing and cleaning easier. Not 100% necessary, but does make life easier once the can gets fouled up.
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Re: 45 Cal Suppressor Design Review

Post by Capt. Link. » Tue Jan 01, 2019 9:16 pm

You could build a coaxial suppressor.Try 1.375 w/ the 1.625 outer tube.The large expansion area works well for blowback operated weapons.
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Re: 45 Cal Suppressor Design Review

Post by Colo32 » Tue Jan 01, 2019 10:06 pm

I haven't done much research on integral or coaxial supressors. I will start searching for those in the forum and see whats involved. If you guys have any links that you can post without too much effort, I would really appreciate it. I can already tell this is going to be a fun learning/building project. The downtime waiting for approval is going to stink!

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Re: 45 Cal Suppressor Design Review

Post by fishman » Tue Jan 01, 2019 10:07 pm

All my cans are 1.625" diameter. Not much reason not to go that big, especially on a 45. It isn't necessary though.
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Re: 45 Cal Suppressor Design Review

Post by Capt. Link. » Wed Jan 02, 2019 1:03 pm

Colo32 wrote:I haven't done much research on integral or coaxial supressors. I will start searching for those in the forum and see whats involved. If you guys have any links that you can post without too much effort, I would really appreciate it. I can already tell this is going to be a fun learning/building project. The downtime waiting for approval is going to stink!
Classic coaxial buzz gun suppressor layout.It features very low backpressure and strong light construction in a compact package.Many variants exist using every baffle known.Sizes range from 12"-9" in the K models.

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Re: 45 Cal Suppressor Design Review

Post by ECCO Machine » Wed Jan 02, 2019 1:07 pm

Colo32 wrote:I included, because I couldn't resist, 2 other "non-typical" designs. I used a 7/16" dia ball for the face port and 1/2" dia ball for the one on the skirt.
I'm not sure it will help, but I don't think it would hurt.
Colo32 wrote: Is the nesting for easier removal/cleaning???
Nesting with full skirts like that also takes the axial load off the cone & plate, allowing you to reduce thickness of those parts to somewhat offset the additional mass of the skirt. K baffles not nested are preloaded by tightening the cap and then stressed with every shot. I have pushed the limits too far, gone too thin with the trepan & broke the plate away, pushed it up over the waist.
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Re: 45 Cal Suppressor Design Review

Post by Colo32 » Wed Jan 02, 2019 5:52 pm

Capt. Link. wrote:Classic coaxial buzz gun suppressor layout.It features very low backpressure and strong light construction in a compact package.Many variants exist using every baffle known.Sizes range from 12"-9" in the K models.
That seems like a very simple concept. It doesn't look like the outer chamber is vented anywhere except where the gasses enter the chamber. Correct? Those holes likely extend the full length of the blast chamber I assume.

Another quick question. With the K-Baffle arrangement and a couple of cones in the blast area, I wont have too many baffles in there. Would it be better to use a lot more tapered cones or radial cones in place of the K's? I would think I could get at least twice as many in the same space.

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Re: 45 Cal Suppressor Design Review

Post by John A. » Wed Jan 02, 2019 6:01 pm

My personal opinion, though I may be entirely wrong because I can't R&D, but since the 45acp has such a large bore hole, and lower pressure to highlight the porting, I just think more radial baffles would work better.
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Re: 45 Cal Suppressor Design Review

Post by Colo32 » Wed Jan 02, 2019 7:41 pm

John A. wrote:My personal opinion, though I may be entirely wrong because I can't R&D, but since the 45acp has such a large bore hole, and lower pressure to highlight the porting, I just think more radial baffles would work better.
My Hybrid 46 has 12 radials in it, and it is very effective. I think for me to turn radials on my CNC lathe would be easier that all the work that goes into K's. I don't really want to replicate what I already have, but adding a coaxial chamber or possibly integral will be different.

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Re: 45 Cal Suppressor Design Review

Post by ECCO Machine » Wed Jan 02, 2019 8:37 pm

Colo32 wrote: Another quick question. With the K-Baffle arrangement and a couple of cones in the blast area, I wont have too many baffles in there. Would it be better to use a lot more tapered cones or radial cones in place of the K's? I would think I could get at least twice as many in the same space.
As I said in my first response, I've found cones to work better than Ks for .45 ACP. To my knowledge, the AAC Ti-Rant is the only current production .45 can using K baffles, everything else is either monocore (yuck!) or some flavor of cone, and lots of them.

This is what makes up my Phoenix XLV-M:

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Since you're (presumably) not trying to make your F1 as heavy duty as the Hybrid, you wouldn't really be duplicating it. You can go a lot lighter, even using stainless for cones. The Phoenix is 12.7 oz with piston, and except for the 7075-T651 front module assembly, is all 17-4 H900 and gr. 9 CWSR Ti
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Re: 45 Cal Suppressor Design Review

Post by Colo32 » Thu Jan 03, 2019 1:07 am

First stab at coaxial design with radials. Can I stack them as shown, or should they be in an inner tube?
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Re: 45 Cal Suppressor Design Review

Post by ECCO Machine » Thu Jan 03, 2019 2:23 am

Looks pretty good. Maybe a little more snout on the baffles, and more, larger holes in the vent tube for the coaxial chamber. And drill them at a compound angle that will force the gasses passing through them to generate a vortex in the coaxial chamber. 45° forward angle, holes drilled offset to one side. Gas that is swirling will fill a space more rapidly and densely, fundamental principal in internal engine intake manifold, port and combustion chamber design.

Trust me, it makes a difference:

https://www.youtube.com/watch?v=S4Ti7S2t5Ns

Colo32 wrote:First stab at coaxial design with radials. Can I stack them as shown, or should they be in an inner tube?
No reason you need an inner tube as long as you have a good system for keeping them aligned. Each baffle in your drawing has a good shoulder, but I don't see what orients the stack on the front cap.
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Re: 45 Cal Suppressor Design Review

Post by T-Rex » Thu Jan 03, 2019 8:57 am

I'm w/ most of what ECCO stated. If you're going with the larger OD, a coaxial is probably the best use of space. The smaller baffle design will allow more to be used. I can't seem to find my dimensional pics of an Octane's radial baffle, but here's what you're going for, more or less.

Image

I, also, missed how the front cap aligned the stack.


As far as drilling the coaxial sleeve's outer holes on an angle to impart spin on the gases: not going to happen. There's not enough wall thickness to create a directional channel. You'll want a minimum 1 diameter of length, to have any appreciable affect. Now, you're recommendation of offsetting the holes to one side can and will do more for you.

Just for some credibility in the matter: this is what I do to pay the bills.

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Re: 45 Cal Suppressor Design Review

Post by Capt. Link. » Thu Jan 03, 2019 10:17 am

I would thread together the entire core if you don't use a inner tube so it can be held in tension.A thin non threaded outer tube can be used and alignment is assured building it this way.

You might add a muzzle brake to the design or use more baffles with the first few vented to the coaxial space.The need for blast chambers is somewhat overrated in low pressure rifle builds as few will suffer from FRP and the gas pressure & temperature is much reduced over a pistol build.

You might also turn a helix on the inner tube with each having a gas port creating several coaxial chambers.This has been used in the past to reduce "Ping" and delay gases,it also gives a softer sound.

I admire your first project being in .45 as its a tough one compared to .22RF-9mm.If in doubt add more frustoconical ported cones to quiet your fears.
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Re: 45 Cal Suppressor Design Review

Post by Colo32 » Thu Jan 03, 2019 12:45 pm

ECCO Machine wrote:No reason you need an inner tube as long as you have a good system for keeping them aligned. Each baffle in your drawing has a good shoulder, but I don't see what orients the stack on the front cap.
I forgot to increase the diameter on the register in the front cap that locates the last baffle in the stack. I will go back and fix that. Sometime today, if I have time, I will make some of the suggested changes and post a few more pictures. I think I will add an inner tube to keep the baffles better contained. I think what I have would be better with the baffles welded together, and I don't want to go there. Today is my weekly range day with the Banshee and G21. Priorities!

Thanks again for every ones input. I like where this is heading.

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