Building a suppressed GBB pistol - Airsoft Sniper Forum

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Old 11-23-2017, 05:00 AM   #1
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Join Date: Nov 2013
Location: Mar del Plata, Argentina
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Grin Building a suppressed GBB pistol

Well kind of a weird, accidental finding kicked off this project;

I was playing around with Poseidon's Ice Breaker piston head for WE GBB pistols, a gimmicky thing with 2 teflon rings instead of the typical oring / seal cup, which is supposed to "improve cold weather performance allowing less gas consumption and more shoots".

Spoiler alert: it certainly does not. It didn't even provide a seal at all, until I opened the clam shell design and put some teflon tape bellow the rings in order to expand them.

After quite some test to adjust the diameter in such way that it provided a good seal while not getting the nozzle stuck, I found something extremely weird: it muffled the sound.
Not just a "I think it sounds somewhat quieter", but a complete modification of the sound signature: the highs and mids get totally cut off. leaving only a bassy "plop" behind, and the perceived volume is about a third of the regular sound or even less.

Kind of makes sense since the sound of a GBB doesn't come from the barrel as it would in a real gun, but is mostly piston pop + metal clings from the working parts. I'm not sure how the Poseidon piston head modifies the piston pop in such a dramatic way, but it certainly does.

In the particular case of my WE makarov the slide noise is already taken care of by a tiny pad /buffer above the trigger guard, and it also includes a suppressor which I'm gonna foam fill (legal down here) just to see if it further lowers the perceived volume.

So there's that. I'll make sure to get some proper DB readings, practical field testing on "how far can you hear that", and maybe some recordings to compare the sound signature.

I might have (accidentally) found the way to achieve a somewhat silent, sniper-worthy pistol without the awful dead feeling of NBBs.

If all of this goes as planned, I might even go into the hassle of turning it into a proper PB to go along with my Russian Army SVD loadout
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Last edited by Dimitri MdP; 11-23-2017 at 05:17 AM.
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Old 11-23-2017, 05:07 AM   #2
Pu7z   Pu7z is offline
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Really interested in this, since I also use a WE Makarov for my VSS loadout.
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Old 11-23-2017, 09:41 AM   #3
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Im looking into building a russian kit, this interests me. Good job! Looking forward to what you are doing.
Don't underestimate me. I know more than I say, think more than I speak, and notice more than you realize.
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Old 02-19-2018, 09:43 AM   #4
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did it work well?
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Old 02-19-2018, 01:05 PM   #5
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Waiting for a new Crazy Jet barrel to go halfway through the suppressor, so I can have full power (330fps) and still use part of it to reduce the sound signature.
I'll update whenever that arrives. Might take a while, horrendous Customs procedures and extremely inefficient Post Office here..
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Old 02-19-2018, 01:19 PM   #6
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Thanks man, it truly sounds interresting tho
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Old 02-19-2018, 08:58 PM   #7
SP3CT3R   SP3CT3R is offline
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Indeed, quite interesting. I'd like to do a somewhat silent pistol build.
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Old 02-20-2018, 09:16 AM   #8
bebna   bebna is offline
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Join Date: Sep 2017
Location: Germany
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I've something similar in the works on both:
  • KJW KP-06 CO2 (HiCapa, still have to wait to get my hands on)
And in the end I want to compare it with a db meter against my VP9. So would be cool to share findings.

NBB isn't really part of this thread, but in my country (Germany) it is very hard to acquire an MK23 NBB. And my goal is to find out, if there is possible alternative for the German airsofter. Let it be NBB or GBB. And like you I think it would be possible to make an GBB silent enough for airsoft, but still the NBB already has proven itself as a learning tool for me, because it showed me already some areas, which generate noise, but I didn't even think about for the GBB.

Before I start with my first points, please let me explain why I focus on CO2. In Germany the climate is colder than those locations where most authors of information I've read about gas pistols are from. Most of the year, green gas pistols are unreliable in there stock form and mags are carried on body, to keep them warm. CO2 works in a wider temperature spectrum, but is often here associated with high power target/plinking pistols, especially CO2 NBB ones. Most of them are not allowed on fields, not because of what they are, but because the often don't pass the 1j limit. Yes, some like the HK USP CO2 NBB shoot almost 1j, but with a fresh capsule they often go easily over the limit and shoot in the range of 1.2j to 1.4j, marshals are also on most fields not stupid enough to let you chrono with a half full capsule or lightweight BBs. The funny thing is, we do want to throttle those guns because of noise reasons, which allows us to kill two birds with one stone, while being able to use the pistol on most game days over the whole year. And yes, I know that I make it harder for myself to use CO2 for a silent pistol build, because of the higher blow back force from the heavier co2 strengthened parts and co2 pressure.

Lastly, I want to add that I don't want to have to use a suppressor. Not everyone wants, can or is allowed to use one. Let it be from legal, look or logistical reasons. For myself, I just don't like them when holstered and I want to keep it free for a tracer. But I will see, what can be done with one and will note my findings of those, too.

Anyway, let us talk about reducing noise. In my opinion there are basically two main systems we can use to categorize our mods: functional based (fire control, blow back and recoil, hop up, gas release and routing, ...) and timing based (before, while and after the shot). Results have to be categorized in if there lessen the level of the sound emitted or only shift them to another frequency. While the former is our goal, while the later is also helpful if a high noise gets converted to a low one, because it is harder to pinpoint for a human.

My current list of ideas by functional part:
1. Fire control
* add rubber or plastic to surfaces who hit each other (Hammer, valve knocker, hammer reset, disconnector, ...)
* add sliding cover to trigger, to seal trigger hole, same for external hammer
* grease moving parts and bearing surfaces
* lighten force the valve knocker / hammer spring

2. Blow back and recoil
* add rubber or plastic to surfaces who hit each other (Travel stops in the blow back housing, slide and slide rails, dampers on the recoil spring, ...)
* reduce force of blow back and tension of recoil spring
* polish and grease sliding / bearing surfaces (frame and frame rails, sometimes between inner-, outer barrel and frame)
* lessen the spring tension of the valve

3. Hop up
* find the optimal combination between the BBs you want to use and the hop up rubber, to achieve optimal hop with the least needed gas pressure

4. Gas release and routing
* use gas routers who don't have hard edges and start to whistle
* optimize the amount of released gas and the barrel length to only have barely enough gas to reach the end of it
* manage how air and excess gas exit the barrel to mitigate noise generated from the pressure difference and other noise generation from the air flow
* polish and grease moving and bearing surfaces (stem of the valve, ...)

5. Magazine and housing
* add a seal to the mag base plate and or funnel
* seal all holes in the frame
* use a textile/camo wrap tape around the whole gun
* use hard foam to fill in as much space as possible to reduce inside air volume
* if there are pieces who touch each other, but don't or shouldn't move, (inner frame in some pistols, fire control housings, ...) disconnect them from spreading sound waves by putting a sheet of rubber or multiple layers of something very thin (aluminum foil) between them

Most important steps seem to be reducing or absorption of impact of moving parts who hit each other and reducing the amount of excess gas. The rest is more "to shed ounces to save pounds" type of stuff.

I think OT creator reduced the impact created by his blow back, by adding friction inside his blow back unit when he added the tape to increase the size of the rings and therefore reduced some noise created by his GBB pistol.

Do you guys got more ideas?
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Last edited by bebna; 02-20-2018 at 09:19 AM.
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Old 06-19-2018, 11:54 AM   #9
bebna   bebna is offline
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Join Date: Sep 2017
Location: Germany
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Update & Push (sry):
I finally got a kjw hicapa last week, but still got problems acquiring an mk23 as reference. Still got some ideas, but it will take time and good portion of luck. Also I just dipped into paintball, so I'm currently out of money. Gonna have to wait till I can buy some parts.

Parts I'm currently looking at:
- Nineball Silent Blowback kit
- (Nineball outer barrel sas + Xcortach XT301 tracer)
- Poseidon Ice valve and piston *
- UAC shock buffers
- maple leaf crazy jet barrel + bucking
- Nineball / uac gas routers *
- Nineball neo R high output valve *

I also got the stupid idea to check how much I can increase gas efficiency while staying in the 0.7-1j range, while having just enough blowback to load the next bb and cock the hammer, but not letting the slide hit the end of it's travel. Probably have to work then with green or duster gas, too.

So do you guys got any other tips or experiences to share?
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Old 07-23-2018, 05:32 AM   #10
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Well, got good news for this one at last.

It works.

And it works wonders. Sure thing it's not as silent as a suppressed non-blowback gun, but sound signature went down to about AEP levels.
Which is noticeable quieter than standard GBB.

I'll do some open field testing as soon as we get a decent weather weekend and report back with some actual readings, perhaps a video comparison as well :)

I'm so turning it into a PB asap
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