How to MOD DonnyFL SUMO LDC VIDEO

I tried to make a funny on the youtube comments section. No disrespect as I'm Asian as well...

"Do I spy a modified chopstick? Typical stereotype. LOL. Dang, now you're gonna make me want to start modding mine even though it's already great. I hope people don't go ripping into their Sealy Posturpedic memory foam mattresses to mod their airgun LDC's....LOL. Good job Ernest."
 
I ended up swapping Donny’s felt for the white foam wrap that plumbers wrap around underground ABS vent and drain pipes that stub up, prior to a concrete pour. That same material was used to wrap up some furniture we recently bought. It quieted my Shogun a lot, while shooting my Hercules 30 cal Bully. If anyone here has that gun, or heard someone shoot one next to them, they know how loud that thing is. The factory felt Donny uses tamed the crack a bit, but not by much. When I swapped the felt for that wrap, big difference.

ive got some of that 1/4” birdscreen(trade term for that wire mesh). I’ll try this mod, and maybe double up on that foam.
 
I have made several silencers in my time. I have tried using packing material of all types from cloth to felt to fiberglass to steel wool and nothing changes the volume. It does have a slight effect on the sound signature, but no change in volume. What does make the biggest difference in sound volume is expansion chamber size. The next item that makes a difference is the number and style of baffles. The idea is to allow controlled expansion of the air. This reduces the pressure and the air velocity. I find it important to create as much air turbulence as possible with the baffle design, as that turbulence reduces the air charge energy before exit and hence, the sound level..You will note that this is the philosophy that FX uses as well with their air stripper and shroud design.

In my experience, the proponents of packing material confuse sound signature change to volume reduction and of course they are not the same. Lastly the emitted sound is different with and without a pellet. That's because pellets are noisy. There is a reason why pellets have a much poorer BC over bullets. They create more turbulence and turbulence is noisy. In the case of air guns, the sound barrier crack is non-existent. What we are hearing is pellet turbulence. A sub-sonic boat tail bullet would be almost silent.

I also believe that the effectiveness of a moderator is reflected in the velocity reduction of the pellet. Where the greater the sound level reduction, the more velocity attenuation occurs. My latest moderator reduces my chosen pellet speed from 940 fps without to 900 fps with. I would like to hear from others to what their speed reduction is with and without their moderator.
 
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It's only $10, by the time you pay for a small piece and shipping you could get this 2'x5' piece.

Everbilt Hardware Cloth

I will add though that I have a new version Emperor and it has a very fine screen between the flight path and the baffle material so no need for me to do this mod but if you have a different version without the internal screen then I would say it would be worthwhile.
 


I also believe that the effectiveness of a moderator is reflected in the velocity reduction of the pellet. Where the greater the sound level reduction, the more velocity attenuation occurs. My latest moderator reduces my chosen pellet speed from 940 fps without to 900 fps with. I would like to hear from others to what their speed reduction is with and without their moderator.

This is a pretty interesting observation. Any idea of the mechanism of the velocity reduction? The only thing I can envision is increased pressure resistance generated as the pellet head approaches the orifice in the baffle or exit. Or increased air density as the pressure wave fills the chamber? Would the number of baffles or orifice diameter affect this velocity loss?



For those who want to go in that direction, far as lining material goes, I think the scouring cloths available in the supermarket cleaning section would be as good as any.
 


I also believe that the effectiveness of a moderator is reflected in the velocity reduction of the pellet. Where the greater the sound level reduction, the more velocity attenuation occurs. My latest moderator reduces my chosen pellet speed from 940 fps without to 900 fps with. I would like to hear from others to what their speed reduction is with and without their moderator.

This is a pretty interesting observation. Any idea of the mechanism of the velocity reduction? The only thing I can envision is increased pressure resistance generated as the pellet head approaches the orifice in the baffle or exit. Or increased air density as the pressure wave fills the chamber? Would the number of baffles or orifice diameter affect this velocity loss?



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I asked that same question on several forums and essentially received BS replies. My first question was; Does the pellet reach the original 940 fps and then slowed to 900 fps or is it that the pellet is prevented from achieving the 940 fps and can only reach 900 fps? I suspect the latter where the speed attenuation is caused by the increased resistance of the air column in front of the pellet. Further, I suspect there is a pressure wave that gets reflected off the first baffle causing this increased resistance.

My experience is that 3 baffles generates the best performance. Adding more baffles does not appear to add better performance. I use conical baffles for stiffness and greater turbulence. I cannot state that conical baffles are significantly quieter, but they are much stiffer. 
 


I also believe that the effectiveness of a moderator is reflected in the velocity reduction of the pellet. Where the greater the sound level reduction, the more velocity attenuation occurs. My latest moderator reduces my chosen pellet speed from 940 fps without to 900 fps with. I would like to hear from others to what their speed reduction is with and without their moderator.

This is a pretty interesting observation. Any idea of the mechanism of the velocity reduction? The only thing I can envision is increased pressure resistance generated as the pellet head approaches the orifice in the baffle or exit. Or increased air density as the pressure wave fills the chamber? Would the number of baffles or orifice diameter affect this velocity loss?

Sorry, I didn't answer in my reply above about orifice size. I always thought that maintaining a tight clearance between pellet and bore diameter was important. I am very careful to maintain perfect concentricity between pellet path and bore diameter and then using as tight a bore as I can, but to be honest, I don't think it is overly important in sound reduction. I think loose works just as well. On my last moderator, it is for a .25 cal. The barrel has a choke which reduces the pellet to .241" My bore size through the moderator is .280". This leaves .020 all around the pellet (.5mm) for clearance. I also made a special tool to verify the bore alignment to the barrel for peace of mind. I think that is important because the moderator mounts to the shroud not the barrel.