All else equal, more baffles or less?

[ken226]

I know that all else is never the same, but for the sake of argument, assuming it were and a suppressor had the same, length, diameter, volume, wall thickness, etc.

Assuming 60 degree conical baffles, and rifle pressures such as .308 and .223, what tends to suppress better, more baffles closer together or fewer baffles further apart? I've seen commercial cans with as many as 8 baffles and as few as 3. Opinions?

[Kuraki]

I think more is better but there is a point of diminishing returns once you get beyond a particular point of chamber space. For instance in a given cylindrical volume, 4 cones offer a particular amount of deflection in ratio to a particular amount of chamber space. 5 cones increase deflection with a reduction of chamber space. 6 again increase deflection, etc etc.

Eventually you come to a point where either the increase in deflection no longer offer appreciable gains or the reduction in chamber space negatively impacts performance.

This is outside of weight, complexity, cost, etc concerns.

[L1A1Rocker]

This came up in a Form 1 build thread a while back. I think the general rule is: Sub-sonic ammunition benefits from more baffles; supersonic ammunition has no benefit to having more baffles but I don't think there is a detriment.

So I think the conclusion is, if you will be shooting sub-sonic ammo go with more baffles. If you are only shooting super sonic ammo and/or weight is an issue (you're going for the lightest possible can) you can use fewer baffles. IIRC, one person went with just three baffles in his and could not tell a difference (to his ear) from a commercial can.

[Capt. Link.]

Once you are below the bullet flight noise there is little reason for added suppression from the shooters perspective. The high velocity gases impinging on the baffles have higher db losses than low velocity gases.I don't know the term a engineer may use for this phenomena but one might add some content. CL

[quietoldfart]

I've no experience with suppressing larger calibres, but if it's any help, I can say that increasing the number of K baffles in the same length of tube on my .22" pistol was a huge help in suppression using subsonic ammunition. It's an integral suppressor about 8" with a 0.87" ID, and about half the volume being over the barrel. The 3.25" available between the barrel mounting vented bronze piece and the profiled front cap is fairly limiting. Initially I used 3 K baffles almost an inch long and a short spacer between the muzzle and the first K. This provided acceptable suppression, but not brilliant.

So I designed a 0.55" long K baffle (which someone here has called an 'X' baffle as the rear section has a 25 degree angle to provide deeper face profiling) with otherwise similar features, and found this to improve suppression quite significantly. After using that for a time it occurred to me that I could increase from 5 of these plus a spacer to 6 by nesting them, reducing the front of each cone to fit into a slightly re-profiled outer face of the next baffle. Going to 6 did indeed improve suppression significantly. After a further while it occurred to me that I might get rid of the spacer tube altogether, and fit yet one more K into the tube for a total of 7. I made this one of steel and profiled it a little more deeply on the face, got rid of the spacer, and was pleased to find that suppression had reached a new low. Very pleasant on the ears indeed, and my cheap meter used in testing all along showed drops of between 1dB and 3dB with the addition of each K, though the overall expansion volume was obviously reduced by the addition of new metal. There is no room for further addition of baffles.

I have also done similar testing with an 11" long tube. The reductions in blast volume as measured by my ears and by the cheap meter have been parallel each time, going from 6 longer K baffles and a spacer gradually down to where it is now at 12 short K's, not nested though, and no spacer. But though it's been similar in improvement through increased number of baffles, the overall benefit of the additional 3" of tube in front of the muzzle has not been terribly significant. Only between 2dB and 3dB overall at each stage. Considering the much increased awkwardness in handling such a long pistol, I've abandoned that suppressor for now. It had the further detriment of being grossly inaccurate with the slowest subsonics I've used; the Remington CBee coming out of my pistol at about 650fps. Seems likely these projectiles are tumbling and clipping slightly, though I've seen no damage at all. Higher velocity rounds are not a problem, but the awkward handling and frankly unsightly proportions of the longer suppressor have put it on the shelf to be used on some other host some day.

[L1A1Rocker]

I've no experience with suppressing larger calibres, but if it's any help, I can say that increasing the number of K baffles in the same length of tube on my .22" pistol was a huge help in suppression using subsonic ammunition. It's an integral suppressor about 8" with a 0.87" ID, and about half the volume being over the barrel. The 3.25" available between the barrel mounting vented bronze piece and the profiled front cap is fairly limiting. Initially I used 3 K baffles almost an inch long and a short spacer between the muzzle and the first K. This provided acceptable suppression, but not brilliant.

So I designed a 0.55" long K baffle (which someone here has called an 'X' baffle as the rear section has a 25 degree angle to provide deeper face profiling) with otherwise similar features, and found this to improve suppression quite significantly. After using that for a time it occurred to me that I could increase from 5 of these plus a spacer to 6 by nesting them, reducing the front of each cone to fit into a slightly re-profiled outer face of the next baffle. Going to 6 did indeed improve suppression significantly. After a further while it occurred to me that I might get rid of the spacer tube altogether, and fit yet one more K into the tube for a total of 7. I made this one of steel and profiled it a little more deeply on the face, got rid of the spacer, and was pleased to find that suppression had reached a new low. Very pleasant on the ears indeed, and my cheap meter used in testing all along showed drops of between 1dB and 3dB with the addition of each K, though the overall expansion volume was obviously reduced by the addition of new metal. There is no room for further addition of baffles.

I have also done similar testing with an 11" long tube. The reductions in blast volume as measured by my ears and by the cheap meter have been parallel each time, going from 6 longer K baffles and a spacer gradually down to where it is now at 12 short K's, not nested though, and no spacer. But though it's been similar in improvement through increased number of baffles, the overall benefit of the additional 3" of tube in front of the muzzle has not been terribly significant. Only between 2dB and 3dB overall at each stage. Considering the much increased awkwardness in handling such a long pistol, I've abandoned that suppressor for now. It had the further detriment of being grossly inaccurate with the slowest subsonics I've used; the Remington CBee coming out of my pistol at about 650fps. Seems likely these projectiles are tumbling and clipping slightly, though I've seen no damage at all. Higher velocity rounds are not a problem, but the awkward handling and frankly unsightly proportions of the longer suppressor have put it on the shelf to be used on some other host some day.

Great post. Thanks for taking the time to write about your experiance. You wouldn't happen to have a thread about your trials and findings with pictures would you? I'd love to see what you did.

[quietoldfart]

Here's the thread where I detail most of what I've done:
viewtopic.php?f=10&t=122425&p=897043
I've now updated it to reflect the addition of a 7th K baffle.

[ken226]

I've done some testing over the last few weeks and i thought i'd post the results here.

I tested 4 suppressors, all on a LWRC 16 inch piston gun, caliber .223. The suppressors were all of my own manufacture, identical designs except as follows.

All were 1.625 od, 7 inches oal, .058 wall thickness.
#1 .275 bore, 7 baffles
#2 .275 bore, 5 baffles
#3 .365 bore, 7 baffles (designed for 300 blackout)
#4 .365 bore, 5 baffles (designed for 300 blackout)

The suppressors with 5 baffles had the same bafflestack length, the 1st baffle being the same distance from the rear endcap to accommodate the Yankee Hill flash hider. They just had more space inside between baffles.

No decibel meter, all by ear. The .275 bore cans were designed for .223 and the .365 bore cans were designed for 300 blackout. All were mounted via a Yankee Hill QD flash suppressor.

The best suppression was from #2. It was easily the quietest. Both the .275 bore suppressors were significantly quieter than the 2 .365 bore suppressors, but #2 also audibly quieter than #1 as well.

Bore diameter made a much bigger difference than i suspected, even moreso than the number of baffles.

After about 300 rounds, i put #3 on my bandsaw and cut it in half to make a cool paperweight.

[c5_nc]

I've done some testing over the last few weeks and i thought i'd post the results here.

I tested 4 suppressors, all on a LWRC 16 inch piston gun, caliber .223. The suppressors were all of my own manufacture, identical designs except as follows.

All were 1.625 od, 7 inches oal, .058 wall thickness.
#1 .275 bore, 7 baffles
#2 .275 bore, 5 baffles
#3 .365 bore, 7 baffles (designed for 300 blackout)
#4 .365 bore, 5 baffles (designed for 300 blackout)

The suppressors with 5 baffles had the same bafflestack length, the 1st baffle being the same distance from the rear endcap to accommodate the Yankee Hill flash hider. They just had more space inside between baffles.

No decibel meter, all by ear. The .275 bore cans were designed for .223 and the .365 bore cans were designed for 300 blackout. All were mounted via a Yankee Hill QD flash suppressor.

The best suppression was from #2. It was easily the quietest. Both the .275 bore suppressors were significantly quieter than the 2 .365 bore suppressors, but #2 also audibly quieter than #1 as well.

Bore diameter made a much bigger difference than i suspected, even moreso than the number of baffles.

After about 300 rounds, i put #3 on my bandsaw and cut it in half to make a cool paperweight.

I really appreciate you doing the work and posting your designs and results. I kind of expected the opposite, I didn't think the the larger holes from the 30cal one you did would perform that much worse, and I expected the tighter stacks ones to out perform the others. Commercial can's are starting to migrate this way, the top performing commercial 5.56 cans are vented tight stacks, and they are moving this to the 30cal models now, like the SDN6.

Observations:

Commercial cans that use tight stacks are typically vented

If anything tighter stacks perform better toward the exit end, like the Surefire 5.56 has what looks like .3" stacks near the exit, that are expand out to about .45-5 toward the barrel. You have a large gap between the end and the final baffle.

The 7 stack design looks like it may be too close to the muzzle, which is probably made worse by using a flash hider instead of a brake. I think what is hurting this is the shorter muzzle to first baffle distance without a brake, otherwise the only thing that should effect the performance is the small amount of volume the the extra two cones take up.

[Capt. Link.]

No subsonics

[ken226]

No, i didn't try any subsonics through these but i have another that is identical to #2 but with clipped cones.. With subsonics it almost perfectly matches our issued UMP.40 with 180 grain subsonic. My coworkers couldn't identify which was the UMP and which was the subsonic blackout.

The UMP has some kind of HK branded swiss made suppressor, not sure what baffle design it has. When we tested these 4, we also had a Surefire Socom with a qd mount. #2 was very similar, subjectively a little quieter. Some of my coworkers thought #2 was a little quieter, some said it was the same in volume but had a lower pitch sound than the surefire socom

#1, and especially 3 and 4 were noticeably louder than the Socom.

a problem i keep running into with this design is alignment. Since the baffles are welded to the front cap, and the front cap welded to the tube, the front cap weld keeps pulling the baffle stack out of alignment. I resorted to tapping 4 holes 90degrees apart in the rearmost baffle, tightening screws into them then turning the screw heads to .001 over the tubes id for a press fit. This is working well so far holding the rear of the baffle stack centered in the tube.



I loaned #2 to a .Gov agency for some torture testing. It'll get a couple thousand rounds put through it in the next 2 days in an M4A1 with lots of full-auto fire. I told them to destroy it if they can, and bring back a smoldering puddle for me to cut open and analyze. I'll post some pics when i get it back and open it up!! It has the 4 screws in the rear baffle for alignment.

I told them to destroy it and i suspect they'll do just that. I do have alterior motives, i admit. The crew have been shooting the piss out of it all morning already, they're really diggin it so far. I suspect ill be making suppressors for alot of these guys personal collections in the near future, providing it holds up well of course.

[a_canadian]

What about making something like this from the same material, maybe 1/4" thick, and drilling and welding through the tube to fix it in place somewhere along the stack as a centering baffle? Carve out as much as is practical for venting into the front space without making it too dainty. I'd probably put it about halfway between first baffle and front cap. Seems it wouldn't unduly reduce efficiency while it'd stabilize the stack much better than 4 screws.

[ken226]

While im certain that would work, im already into each one for about 10 hours, that looks like it would add another hour or two.

The screws im using are stainless button head screws, thread into the baffle from the outside. I put the baffle assembly between centers and turn the screw heads down just enough to be a press fit.

I like that idea, ill make one and see how long it takes. If it goes faster than an hour, i'll use the idea.

[colimr]

The movement in the baffles is caused buy the differing heat expansion in the weld,cap and baffle stack . The baffle stack should be seperated from the cap so that the heat expansion is more uniformed than being affected by the weld.Just an opinion from welding .As the weld warms it expands and retreacts as it cools think of power lines in summer they droop and winter they are tight.Dissimular metals and all good luck

[a_canadian]

Another idea, maybe better. What about three or four splines running the full length of the baffle stack? You weld the stack together, then tack a 0.065" or so plate to each baffle back to front, slightly wider thanethe gap between stack and tube ID. Then just chuck it up, centering on a rod close to the same diameter as the bore, and turn down these 'fins' until they're a press fit. It'd take a very sharp cutter and just the right spin and feed rate so you're trimming, not bending, but seems simpler then the vented ring and welding through the tube, plus it 'passes gas' more effectively. Some 1/16" x 1/8" stock would do it maybe.

[colimr]

just my opinion,I would seperate the baffles from the cap and use a vented blast baffle the od of the baffle cone with a bushing at cap end and back end to center and hold the stack allowing for expansion and contraction.This would allow the stack to expand up and down and in and out while loosing a vary small amount of current available expansion chamber it may also cause the pressures to be redirected a bit making a slight sound change

[Capt. Link.]

No, i didn't try any subsonics through these but i have another that is identical to #2 but with clipped cones.. With subsonics it almost perfectly matches our issued UMP.40 with 180 grain subsonic. My coworkers couldn't identify which was the UMP and which was the subsonic blackout.

The UMP has some kind of HK branded swiss made suppressor, not sure what baffle design it has. When we tested these 4, we also had a Surefire Socom with a qd mount. #2 was very similar, subjectively a little quieter. Some of my coworkers thought #2 was a little quieter, some said it was the same in volume but had a lower pitch sound than the surefire socom

#1, and especially 3 and 4 were noticeably louder than the Socom.

a problem i keep running into with this design is alignment. Since the baffles are welded to the front cap, and the front cap welded to the tube, the front cap weld keeps pulling the baffle stack out of alignment. I resorted to tapping 4 holes 90degrees apart in the rearmost baffle, tightening screws into them then turning the screw heads to .001 over the tubes id for a press fit. This is working well so far holding the rear of the baffle stack centered in the tube.



I loaned #2 to a .Gov agency for some torture testing. It'll get a couple thousand rounds put through it in the next 2 days in an M4A1 with lots of full-auto fire. I told them to destroy it if they can, and bring back a smoldering puddle for me to cut open and analyze. I'll post some pics when i get it back and open it up!! It has the 4 screws in the rear baffle for alignment.

I told them to destroy it and i suspect they'll do just that. I do have alterior motives, i admit. The crew have been shooting the piss out of it all morning already, they're really diggin it so far. I suspect ill be making suppressors for alot of these guys personal collections in the near future, providing it holds up well of course.

Bravo on the tests.I you did do a subsonic follow up the results are predictable.If you ever need a can destroyed I find the M249B can fulfill your every need. I like the large volume coaxial design and the benefits it gives.While smaller size is great most folks don't hump there equipment out to the boonies and back and longevity is more important.Unless I missed it did you use 304 the welds are sweet!

[ken226]

I used 4130. The welds are fusion tig'd, no filler, just a .001 press fit, and followed the seam with the tungsten. I used a Tig machine that uses an IGBT squarewave inverter, set at 4 pulses per second. Pulse peak set at 65 ams, pulse trough at 35 amps with 40 amp start and end power.

I made a welding rotisserie out of a Chinese wood lathe headstock, it rotates the suppressor at 1.25 rpm. All I have to do is rest my arm on an old ammo can, hold the tungsten still and the machines do the rest.

[gunny50]

While im certain that would work, im already into each one for about 10 hours, that looks like it would add another hour or two.
The screws im using are stainless button head screws, thread into the baffle from the outside. I put the baffle assembly between centers and turn the screw heads down just enough to be a press fit.
I like that idea, ill make one and see how long it takes. If it goes faster than an hour, i'll use the idea.

I solved it by making a larger blast baffle that fits outer tube and machined all material away on mill with rotary head except for 4 fingers.



Only takes a few minutes on the mill when all is installed and ready to go.
Worked perfect on my MP5 cans


Gunny

updated with picture.

[ken226]

Very nice gunny, ill be experimenting with some versions of that this weekend!

Yesterday they got about 500 rnds through it, including about 6 full-auto mag dumps on an M4A1

Today another appx 500 more rounds more, and some more full auto including a few mag dumps. All on an HK 416. At one point, the center of the tube section was visibly glowing and the cerakote is gone, leaving the parkerizing.

They said that it was audibly quieter by the end of the day! I didn't really anticipate that it would get a little quieter with lots of use. Carbon buildup possibly dampening the way the soundwaves travel through the steel?

The only complaint was lots of gas blowback on full-auto. I'm not really sure what can be done about that with regards to the suppressor design.

[gunny50]

Very nice gunny, ill be experimenting with some versions of that this weekend!
Yesterday they got about 500 rnds through it, including about 6 full-auto mag dumps on an M4A1
Today another appx 500 more rounds more, and some more full auto including a few mag dumps. All on an HK 416. At one point, the center of the tube section was visibly glowing and the cerakote is gone, leaving the parkerizing. They said that it was audibly quieter by the end of the day! I didn't really anticipate that it would get a little quieter with lots of use. Carbon buildup possibly dampening the way the soundwaves travel through the steel? The only complaint was lots of gas blowback on full-auto. I'm not really sure what can be done about that with regards to the suppressor design.

Could you make a picture with the Flashider inside the can that you cut in 2?
By looking at the sectioned can I guess the diameter of the inner core is 1.25" ?
Wall on baffles around 0,058 as well?
The blast-chamber where the FH sits about 1,5" long / short.
Your blast baffle also in 4130?

4130 combination with ultra short blast chamber and FH on the barrel and short barreled weapons will have a relatively short live on the blast baffle. You can TIG / Fusion weld Inconel to 4130 with the right filler
Shortening your inner core by making last baffle come closer to the endcap (loose the straight wall section), will be better in performance and less gas blowback as gas can expand better in larger blast chamber before hitting the inner core.
A dual design like yours should have less blowback but it realy needs enough distance for the gas to expand before hitting the blast baffle.
Cerakote gone, so I guess you used the bake on type as I did tests with the air drying coating (high temp.) and it holds up well for the micro cans on a 10,5" barrel.

Gunny

[Pat M]

Kuddos and many thanks to you guys for a great informative post, i'm sure this will make mine and many other's suppressors better

[ken226]

Yea Gunny, your spot on with the specs. Inner core is 1.25 OD, outer tube is 1.625 OD, .058 wall and 1.509 ID. Blast chamber is 1.5 long. It fits the YHM .223 1/2-28 and the YHM .30 LTE 5/8-24 QD flash hiders. The YHM .308 flash hiders are too long.

I had already been intending to incorporate the change you suggested, shorting the forward most baffle, increasing the length of the blast chamber. It should prolong the life of the blast baffle and allow it to fit the YHM .308 flash hiders as well.

The blast baffle is 4130 as well. I've thought about trying an inconel blast baffle, but have been a little apprehensive about trying to machine it since i primarily use HSS tooling. Luckily, i have the ability to have 10,000 rounds of 5.56 put through this suppressor in a real short time by guys who get paid to shoot, it won't cost me a penny. I'll split it open in a few weeks and see how the blast baffle has taken the abuse.

[gunny50]

Yea Gunny, your spot on with the specs. Inner core is 1.25 OD, outer tube is 1.625 OD, .058 wall and 1.509 ID. Blast chamber is 1.5 long. It fits the YHM .223 1/2-28 and the YHM .30 LTE 5/8-24 QD flash hiders. The YHM .308 flash hiders are too long. I had already been intending to incorporate the change you suggested, shorting the forward most baffle, increasing the length of the blast chamber. It should prolong the life of the blast baffle and allow it to fit the YHM .308 flash hiders as well. The blast baffle is 4130 as well. I've thought about trying an inconel blast baffle, but have been a little apprehensive about trying to machine it since i primarily use HSS tooling. Luckily, i have the ability to have 10,000 rounds of 5.56 put through this suppressor in a real short time by guys who get paid to shoot, it won't cost me a penny. I'll split it open in a few weeks and see how the blast baffle has taken the abuse.

Ken, sounds great.
Could you post a picture with the FH in the can as mentioned above?
This will help other to visualize better for future projects as well.
Keep u posted on the outcome, love to see what 10K rounds do to the blast baffle.
What gun / barrel length are they using for this endurance test?

Gunny

[ken226]

Oddly enough, i don't own a .223 or .30 LTE flash hider, both of my YHM flash hiders are .308 versions and too long to fit the cutaway. I'll get a pic today at work and post it this evening when i get home.