action noise and suppressor hosts

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Re: action noise and suppressor hosts

Post by John A. » Mon Sep 03, 2018 3:45 pm

Capt. Link. wrote:At this point in time we must build a quieter machine.-CL
Yep, the time has come.

There was a time when the low 120's was about as quiet as was possible.

Now we're routinely down into the one teens.

I don't believe anything is going to be able to achieve any better than that, unless host noise is addressed.
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Re: action noise and suppressor hosts

Post by Capt. Link. » Mon Sep 03, 2018 4:28 pm

John A. wrote:
Capt. Link. wrote:At this point in time we must build a quieter machine.-CL
Yep, the time has come.

There was a time when the low 120's was about as quiet as was possible.

Now we're routinely down into the one teens.

I don't believe anything is going to be able to achieve any better than that, unless host noise is addressed.
John A I know of at least one integral .22 pistol that was measured @ 106db w/ subsonic ammo and based upon the MK2. Best equipment money can buy using Mil standard testing of the day.The pistol did not cycle so breech noise was absent.The Anfibian is another that is dead silent when wet or dry.Other than a little action work the MK1,2,3,4 series of pistols are very silent hosts.We could use a modern version of the P9,P7/13 series for a major caliber pistol.
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Re: action noise and suppressor hosts

Post by a_canadian » Mon Sep 03, 2018 4:33 pm

Has anyone built a .22lr can get using similar principles to what is used in those sound laboratory negative decibel rooms? I can see such long conical shapes being adapted for use in a rimfire can in a couple of ways: welding hollow pencil-tip-like cones (or perhaps elongated pyramidal cones) into thin tubular rings and stacking these as a series of 'baffles' (probably best to put one or two washer type baffles in there too), or rendering long thin cones as the complex internal structure of a monolithic sintered metal 3D printed device. Perhaps I've missed such experiments, but in years of looking at cans online I've yet to see anything like that. Seems bound to absorb sound and break it down via complex destructive interference, more effectively than K baffles perhaps.

Owing to the cones converging in a cylindrical suppressor tube it would likely prove more effective if done in a rectangular body. Easier for assembly as well. Just spread flux on a piece of sheet metal (oversize to prevent warping due to heat) and lay out your grid of cones within a marked rectangular area, then sweat in a layer of silver-bronze alloy rod with a torch, then trim to shape and tig weld four of these panels together. A bit fussy figuring out how to achieve a proper bore placement and size but not rocket science. I'm guessing such a pattern could be scaled for various levels of suppression efficiency just using smaller or larger panels and cone sizes. Tricky too would be cones interfering with each other... So maybe an alternating grid pattern from just two sides if using longer cones, or stick to shorter ones and have them on all four sides.

Another notion; do the same as above except with a single sheet of steel, alternating 8 rows in a zigzag pattern. Trim to finished length and width after it cools, then crease 7 times between the rows and fold the thing together for an octagonal can with maybe 100 little teeth facing each other. Make them tornado shaped for increased air volume. Weld on end caps and you're done.

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Re: action noise and suppressor hosts

Post by Capt. Link. » Mon Sep 03, 2018 6:24 pm

They are called Anechoic chambers.....we always called them dead rooms, they are creepy to work in for extended periods.
https://en.wikipedia.org/wiki/Anechoic_chamber
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Re: action noise and suppressor hosts

Post by a_canadian » Mon Sep 03, 2018 7:12 pm

I don't mind creeping out a bunch of subsonic bullets ;-)

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Re: action noise and suppressor hosts

Post by DKDravis » Tue Sep 04, 2018 9:04 am

The principles from "Anechoic chambers" probably won't do much to eliminate the noises from a firearm, unless you shoot inside such a chamber .. The effectiveness of the "cones" in an anechoic chember relies on the wavelength of sound being in the range of the physical size of the cones, ant the cones are made from absorbing/soft material.

Most of the noise made by the actual "chemical propulsion" of a bullet comes from expanding gasses. These expanding gasses makes pressurewaves or "soundwaves" but the wavelength of the resulting "sound" will be so much longer that the small cones you can put inside a suppressor will have no effect, quite apart from the fact that they can not be madefrom a soft sound absorbing material :)

The bullet still "uncorks" inside the suppressor, so an expanding pressure wave is still created inside the "can" .. The "uncorking" pressure must be low to ensure a good suppression- thus a longer barrel helps -- If the powder charge propelling the bullet is very small, there is a very small amount of gas, and the pressure drops very rapidly .. this can be experimented with in the virtual world of "Quickload" -- :D
This "uncorking" inside the can I believe is what sometimes makes some cans have a sharp "ping" sound quality to them.
Certainly my Ase-Utra SL5 has a much sharper sound to it without its kevlar cover.

The mechanical noise of a semiauto firearm, coupled with the escaping (and expanding) gasses through the action, can only be mitigated by constructing the action to make as little noise as possible and keeping the breech closed until the pressure has dropped to near atmospheric levels. Even the 30-50 PSI of a normal compressor air -hose makes quite a loud POP - if you "uncork" it-

The only alternative to this is to enclose the entire action in a soundproofed/deadening "box" - That could also process the fired cases. While this may seem a cumbersome approach, it might actually be feasible, and would add the extra benefit of not dropping spent cases "on the scene"
Perhaps the route of using a repeater of some sort (Bolt/lever/straight pull -- ) is more feasible-
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Re: action noise and suppressor hosts

Post by a_canadian » Tue Sep 04, 2018 11:33 am

A) I highly doubt that the foam cones in an anechoic chamber are sized to somehow 'match' the wavelengths of all sounds tested within such chambers. I am reminded of some cool in 19th century Scotland who would break up violins into something around 234 pieces of varying lengths and widths in an attempt to secure 'matching' vibratory bodies for every single note played upon the instrument, carefully gluing these puzzle pieces back together. A writer at that time described his assessment of such madness as such: "While this is an excellent testament to the acoustical properties of glue, I find that it is altogether too much of a muchness." I've seen photos of several university sound laboratory anechoic chambers. The cone sizes are not nearly so randomized as to account for all the many frequencies of sound one might generate within. In fact there are only a few sizes of cones in such labs, scarcely sufficient to cover the thousands upon thousands of frequencies generated by widely varying test sources.

B) Perhaps you are not aware of harmonics as a central aspect of the behaviour of sound waves? Even partials (another term for these intimately related frequencies) several octaves above our range of hearing can have large influences upon the perceived sound. Similarly it seems not a stretch to theorize that scaled cones might interfere with 1/2, 1/4, 1/8 or even finer ratios of a given audible frequency of sound wave, as a basic function of acoustical geometry. One need not match the wave to a similarly scaled cone set. Only provide an opportunity for waves to be redirected such that they set up destructive interference patterns, and then the impulse aggressively contributes to its own demise. This 'uncorking' is meaningless. Sound is sound, regardless of the source. Sound can be manipulated via reflection. The particular medium - expanding combustion gases and air in this case - makes a difference only in that propagation locally, within the gas itself, is likely to be faster due to gas density, much as sound travels several times faster in water (varying by salinity).

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Re: action noise and suppressor hosts

Post by ECCO Machine » Tue Sep 04, 2018 12:08 pm

a_canadian wrote:Has anyone built a .22lr can get using similar principles to what is used in those sound laboratory negative decibel rooms? I can see such long conical shapes being adapted for use in a rimfire can in a couple of ways: welding hollow pencil-tip-like cones (or perhaps elongated pyramidal cones) into thin tubular rings and stacking these as a series of 'baffles' (probably best to put one or two washer type baffles in there too), or rendering long thin cones as the complex internal structure of a monolithic sintered metal 3D printed device. Perhaps I've missed such experiments, but in years of looking at cans online I've yet to see anything like that. Seems bound to absorb sound and break it down via complex destructive interference, more effectively than K baffles perhaps.

Owing to the cones converging in a cylindrical suppressor tube it would likely prove more effective if done in a rectangular body. Easier for assembly as well. Just spread flux on a piece of sheet metal (oversize to prevent warping due to heat) and lay out your grid of cones within a marked rectangular area, then sweat in a layer of silver-bronze alloy rod with a torch, then trim to shape and tig weld four of these panels together. A bit fussy figuring out how to achieve a proper bore placement and size but not rocket science. I'm guessing such a pattern could be scaled for various levels of suppression efficiency just using smaller or larger panels and cone sizes. Tricky too would be cones interfering with each other... So maybe an alternating grid pattern from just two sides if using longer cones, or stick to shorter ones and have them on all four sides.

Another notion; do the same as above except with a single sheet of steel, alternating 8 rows in a zigzag pattern. Trim to finished length and width after it cools, then crease 7 times between the rows and fold the thing together for an octagonal can with maybe 100 little teeth facing each other. Make them tornado shaped for increased air volume. Weld on end caps and you're done.
While all sound is pressure, the particular sound of gunshots is the suddenly escaping ("uncorking") pressure, same as rupturing a pressure vessel, disconnecting an air hose, air guns, etc. Suppressors don't work by mitigating the acoustic waves like a dead room, but by slowing the flow of the gasses that are uncorking, giving them more time to cool & contract, ergo reducing the pressure that vents out the front.

See DKDravis reply, he explained it well.

One of the challenges faced in trying to bring the SPL much lower than we've managed to so far is the fact that there's no way around having a hole right through the center of our muffler. The noise produced by an IC engine can be just as high (sometimes higher; nitromethane dragsters will meter 150+ dB at 100 feet or more) than a gunshot if measured right at the exhaust port or short tube off of it. But the amount of length & volume, and being able to completely eliminate laminar flow by making all of the exahaust gasses change direction are why we can take the noise of an IC engine combustion cycle from 150 down to 80.

The other challenge is making it practical; if it's 2 feet long and weighing 5 pounds, I don't care how quiet a suppressor is, I'm not interested, and I would wager that I speak for the overwhelming majority of the market. Sales trends indicate that 1.5x 8" is about the most people will readily tolerate on handguns or sporting rifles, with 1.75" x 9"-10" being the upper end of what will sell at all other than necessarily monstrous 12 ga and .50 BMG cans. I know the idea behind this thread is what can be done at all, not what can be done practically, but I don't feel you can divorce possible and practical to that degree where firearms and suppressors are concerned. To wit, we wouldn't even be discussing the semi-auto if quietest possible gunshot were the single important factor. Running with that, what's the point of an uber-quiet semi-auto if it can't be made reliable and practically useful?

Many of you haven't known me long enough to realize that the work I do is well more than building silencers and threading barrels. I've built some of the lightest weight prototype rifles you're likely to ever encounter, from a 3.48 pound autoloading 9mm carbine to a 19 ounce .22 bolt action (both title I, not SBR). Are they absolutely as light as could be done? Of course not. They are, however, as light as can be made practicably from a durability and utility standpoint. I see little use in pushing the limits of possible to end up with something completely impractical or unworkable. I would make it analogous to the automotive world r.e. the aforementioned nitro dragsters; they make over 10,000 HP and accelerate to more than 300 MPH in less than 4 seconds. Is that the most horsepower possible from a big, supercharged nitromethane V8 engine? Not even close. But what's the use in having 15,000 horsepower if it can't be put to the ground due to limitations in traction? The answer is none. And that's why, while I still consider it an interesting mental exercise, I won't personally invest time and energy into developing a suppressed weapon system that gives up portability, usability, reliability or durability to shave a few more dB from the total noise. With semi-autos, even if you manage to deaden the sound of the bolt reciprocating and stopping, you still have rounds being stripped from the magazine and pushed into the chamber, and while I don't have dB figures on doing that even by slow manual action, consider the noise made in cycling any bolt action rifle. I would wager that even with little bumpers that all but eliminate the noise from the bolt hitting the breech face, you're still gonna be near if not over 100 dB dropping the bolt on any rimfire autoloader. I'll check that and post back once I have my new mic for the B&K meter.

As well, the practical and possible limitations of reducing autoloader action noise are further compounded by the significant perception of suppressors already being the tool of an assassin. It's been fairly easy to counter that with videos and explanations that demonstrate real world suppressors being far from the Hollyweird representation and using that in conjunction with data showing what is hearing safe. It's pretty easy to defuse even the most rapid anti's arguments by pointing out that the typical suppressed gunshot is in the 115-140 range, making the firearm safer to use but far from audibly undetectable. I think in the current climate, we would actually do ourselves a disservice to make highly specialized weapon systems that are so quiet you actually can't hear the shot from the next room.

All that said, I think if you wish to effectively reduce the action noise much below the sound of the actual shot, you need to be looking in a completely different direction. As in, rather than trying to limit the SPL of mechanical noises, how to not make them in the first place. The short answer is that you're not going to accomplish that well if you continue to address it with firearms that use gas or recoil energy to cycle the action. What you essentially want is a manual action that is cycled automatically, and you get that with electronics. With electric motor driven autoloading systems, you can eliminate every fast-moving spring-dependent mechanism but the striker or hammer (that, too, with electronic ignition like Remington E-tronix). You can program it to not cycle for however many milliseconds after the shot to let bore pressure attenuate, eliminating port noise. You can have the bolt unlock & move at any speed you want. You can have the rounds presented before the chamber in a number of fashions that will minimize or even elimate the noise of stripping them from a magazine. You can have buffers & bumpers in place which deaden any remaining mechanical noise which wouldn't be possible due to durability with a completely mechanical action, but with the slower movement of a servo action, can actually last. You can tie the ejector into the electromechanical system so that it is more a remover, even something like a little arm that pushes the spent case into a cavity in a piece of foam attached to the port. And you can do all this with a pretty normal looking firearm, without any particularly unusual or cumbersome apparatus.
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Re: action noise and suppressor hosts

Post by John A. » Tue Sep 04, 2018 1:00 pm

By and large, semi's are going to be gas operated.

I do agree that there would be options like you mentioned, but I'm not a huge fan of electronics. For a myriad of reasons. But you could in effect do an electronic action. An electromagnet firing pin and even the bolt could be electronically operated. And as long as you have enough power, could even make some guns more reliable in prolonged use.

They could even be programmed with a preset rates of fire to reduce wasted ammunition and to make the gun more accurate in full auto fire (thinking military use here). But I don't think would be the "next" step. And I was serious about not being a fan of electronics. Too easy to disrupt them. EMP, Jammers, dead batteries, etc.

And all the technical work it would take to do everything I just wrote is far above my pay grade.

I do still like the ejection port idea. I do think it would redirect the sound of the shot at the ejection port. Perhaps it wouldn't "absorb" the sound waves and certainly wouldn't eliminate it altogether, but redirecting them to the ground does seem feasible. Even as simple as that is, is still a better alternative than they currently are.

Another thought about bolt clack, which is where much of the action noise sound comes from, in some guns, would be possible to install a polymer inset in the face or a ring around the face of the barrel so when the bolt smacks up against it, would be a buffer and deaden some of the sound. I think we're all familiar with that sound. But it sure would be nice to seriously reduce or nearly eliminate it.

There are lots of actions that are really quiet now. Bolt, lever, locked actions. But there are aspects to all of them that could still be improved upon.

As for the politicians and activists and lobbyists, they already demonize and loathe gun owners in any way they think they can. This topic isn't going to change that if it were locked right now.
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Re: action noise and suppressor hosts

Post by ECCO Machine » Tue Sep 04, 2018 6:01 pm

John A. wrote: I was serious about not being a fan of electronics. Too easy to disrupt them. EMP, Jammers, dead batteries, etc.
I tend to agree fundamentally, but would also say that by the time you deal with all those other noises in a strictly mechanical & gas design, you're going to have a lot of maintenance and reliability issues as well-probably more.

With battery technology today, specifically Li-Ion, LiFe and LiPoly, it's far from the situation we had even a decade ago. Back when I was a kid, top of the line electric RC cars got spanked by even small engine nitros, and NiCd or the later NiMH batteries gave you maybe 10 minutes hard run time. And they smoked analog & digital speed controllers on a regular basis. Today, the cheaper RTR brushless RC cars will beat the pants off nitros in their class, easily run 30-40 minutes on a lightweight LiPoly battery, and can pretty much take a nose dive off a cliff with no detriment to the receiver, servos or speed control.

A firearm system would be closed, no transmitter/receiver that can be interfered with, so jamming signals is a non-issue. I don't personally consider EMP a real threat in general, and if a high E1 impulse, high altitude blast occurs, I'm gonna have bigger problems than my special suppressed gun becoming a manual action.

As for the complexity of the electronic system, it doesn't have to be any more than a simple circuit with a battery, gear motor & a couple micro switches. Simplifying the electronic side necessarily complicates the mechanical components a little bit, but the degree of complexity depends on how much you want it to do.
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Re: action noise and suppressor hosts

Post by fishman » Tue Sep 04, 2018 9:45 pm

I do agree that there would be options like you mentioned, but I'm not a huge fan of electronics. For a myriad of reasons.[...] And I was serious about not being a fan of electronics. Too easy to disrupt them. EMP, Jammers, dead batteries, etc
Why does this sound familiar?
Oh yeah!
When you make all your design choices based on absolute maximum suppression, you lose so many other things in the trade offs of those decisions
If you want absolute epitome of quiet, then shoot a long barreled break action integrally suppressed 22short. Wet with wipes. Make a few simple mods to quiet the hammer and the action snapping shut. Done.
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Re: action noise and suppressor hosts

Post by cdhknives » Tue Sep 04, 2018 11:43 pm

fishman wrote:
I do agree that there would be options like you mentioned, but I'm not a huge fan of electronics. For a myriad of reasons.[...] And I was serious about not being a fan of electronics. Too easy to disrupt them. EMP, Jammers, dead batteries, etc
Why does this sound familiar?
Oh yeah!
When you make all your design choices based on absolute maximum suppression, you lose so many other things in the trade offs of those decisions
If you want absolute epitome of quiet, then shoot a long barreled break action integrally suppressed 22short. Wet with wipes. Make a few simple mods to quiet the hammer and the action snapping shut. Done.
I'll go one further since we're going to extremes...an electrically fired muzzleloader at Flobert BB power levels. No action noise and reed switches are really REALLY quiet.

Or just use a PCP air rifle. No stamp required for the suppressor and useful power levels.
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Re: action noise and suppressor hosts

Post by a_canadian » Wed Sep 05, 2018 12:11 am

Problem with most PCPs is that they're not efficiently tuned, resulting in noise levels disproportionate to their power level as compared to rimfire. Tuning a PCP is a complex affair involving a lot of trial and error, aided by a couple of particularly helpful hobbyists who share data and experiences in forums. But most folks either haven't the skills to follow up such work or just don't care, resulting in too much air dumping down the bore for a given power at the muzzle, and too much air for even a very well made suppressor to take all the sting out of the report. The newer guns from FX offer easily adjustable hammer strike, valve porting, and regulator preset pressure, but even there it takes a lot of trial and error to render an efficient enough balance of these controls to make for decent suppression efficiency.

And there's the subjectivity problem. Seems a whole lot of folks in the suppressor community (airgun forums included) are only too cheerfully saying 'the only sound I hear is the firing pin drop (or hammer/striker for a PCP), when of course that's complete nonsense. Even if you're shooting CCI Quiets out of a 25" barrel with a state-of-the-art suppressor costing you $1,000 or more, 112dB or louder is one hell of a lot more than the firing pin noise. Problem is, most adult shooting enthusiasts have more hearing damage than they know or will admit. Hearing loss is very common. And if you've ever shot firearms unsuppressed without good hearing protection (properly inserted foamy plugs or active electronic plugs + good external earmuffs) you're among those who hear less sound than is being generated. If in addition you attended a few too many loud musical events in your youth, well, you're just not a reliable source of opinion when it comes to suppressor efficiency. If you also work in a loud job and don't always remember your hearing protection you can forget about anyone taking you seriously about this stuff. It's really nice of a friend of mine to say my latest can is so quiet he can't tell whether I've fired yet or not... but considering the 1.5million or so rounds he's put downrange professionally, I just smile politely and don't take it to heart. I tend to take my son's opinion more seriously. He's not a teenager yet and has always been excessively sensitive to loud noises, so when he tells me something's pretty quiet, that's a solid review. He shoots a PCP, but wouldn't until I got it tuned so well and shooting at about 9.5fpe that even unsuppressed he didn't complain, so suppressed it's 'stupid quiet' which is good enough for his delicate eardrums.

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Re: action noise and suppressor hosts

Post by zevdogs » Wed Sep 05, 2018 9:15 pm

My bolt is much louder than my suppressor on my Ruger 10/22 I made several years ago, i’ve even add dampening things but it didn’t help too much
check it out
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Re: action noise and suppressor hosts

Post by John A. » Wed Sep 05, 2018 10:10 pm

Nice work on those.
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Re: action noise and suppressor hosts

Post by doubloon » Thu Sep 06, 2018 12:25 am

Nice toys zev!
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Re: action noise and suppressor hosts

Post by alordnapa » Sat Sep 08, 2018 2:23 pm

I have experimented with electrically operated 10-22's. These used a solenoid to manually cycle the bolt when firing Colibri .22 "LR" rounds, which are quieter than a suppressed rifle from my 24 inch barrel. The gun is not intended to cycle the bolt in relative slow-motion, so it was too quirky to work with. A weapon built from the ground up as electrically operated, like the Mini-Gun, would be ideal Phase II may be to try and build a green-gas powered 10-22, running uber subsonic rounds like the Colibri. I found a Bolt that will let my 24 inch barreled 10-22 feed and cycle .22 "Quiet" ammo, which is still quieter than most suppressed blowback .22 rifles. Its not always possible to find this ammo, so I would have to change bolts when I changed ammo, or the bolt would be beaten to death.

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Re: action noise and suppressor hosts

Post by yondering » Sun Sep 09, 2018 2:03 am

Along the lines of quieting action noise - there is an industrial product in the automotive industry called "quiet steel". It's a laminate sheet metal that's engineered to be acoustically dead; it doesn't ring or clank when struck or dropped, but instead has a very muted flat "thud" sound. I'd like to see that technology applied to firearm receivers and possibly bolts. It might have some value in suppressor tubes too, although I don't remember the temperature limits.

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Re: action noise and suppressor hosts

Post by John A. » Sun Sep 09, 2018 8:14 am

I'll have to look into that. I hadn't ever heard of it before.
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Re: action noise and suppressor hosts

Post by yondering » Sun Sep 09, 2018 9:38 pm

I don't know if it's commerically available in small quantities, but the concept could be applied with a bit of engineering.

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Re: action noise and suppressor hosts

Post by cdhknives » Mon Sep 10, 2018 12:13 pm

https://www.materialsciencescorp.com/pr ... uiet-steel

Interesting. Might be able to build stamped receivers like this. I don't how you would machine it and retain the properties. Some method of covering a receiver to create a similar effect could work too, similar to spray on sound deadening materials with an additional hard outer shell for durability.
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Re: action noise and suppressor hosts

Post by John A. » Mon Sep 10, 2018 12:43 pm

cdhknives wrote:https://www.materialsciencescorp.com/pr ... uiet-steel

Interesting. Might be able to build stamped receivers like this. I don't how you would machine it and retain the properties. Some method of covering a receiver to create a similar effect could work too, similar to spray on sound deadening materials with an additional hard outer shell for durability.
I was about to mention sound deadening spray.

Vehicle undercoat.

Flex Seal and the sorts.

While this wouldn't work on baffles obviously, there are other places that it could be applied to.

I was laying in bed having a hard time to go to sleep last night and was thinking about this topic while waiting for my body to wear on down and go to sleep.

One way to make an ejection port for AR15 uppers, you could use the ejection port door pin and remove the cover and install the deflector.

Just thinking out loud.
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Re: action noise and suppressor hosts

Post by yondering » Mon Sep 10, 2018 8:59 pm

cdhknives wrote:https://www.materialsciencescorp.com/pr ... uiet-steel

Interesting. Might be able to build stamped receivers like this. I don't how you would machine it and retain the properties. Some method of covering a receiver to create a similar effect could work too, similar to spray on sound deadening materials with an additional hard outer shell for durability.
It was described to me by the supplier as something that could be machined, drilled, punched, and even welded. Obviously welding would impact the "quiet" properties along the weld, but the rest of the part is supposed to be fine.

It should be fairly straightforward to build existing metal receiver designs (like HK or Uzi) out of this stuff, although I don't know how much those actions would benefit. The Uzi seems to clank a lot though so it might be a big improvement.

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fishman
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Posts: 1444
Joined: Sun Dec 20, 2015 9:15 pm

Re: action noise and suppressor hosts

Post by fishman » Tue Sep 11, 2018 12:29 pm

Flex Seal
Image
We've replaced this UZI receiver with a screen door!!!



Carry on with your productive discussion. Don't mind me.
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293

5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647

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