How to improve my DIY springer moderator?
Today I made a PVC moderator to tone down an unusually loud (to me) springer. This is a Chinese XS25 in .22 which has been de-tuned to 11 fpe and also has a barrel chopped to 14.5″. I was surprised at the noise level – it is as loud as another springer shooting 15 fpe. Some of it is a noiser powerplant, some of it was airblast. Yeah yeah yeah – I know – many feel a springer can’t be moderated, but in my experiment I found it really helped.
I built a 1″ PVC moderator to take the edge off the muzzle blast. Design is a ventilated steel pipe wrapped in Scotchbrite pad and centered inside a 1″ PVC using wraps of duct tape to center it. Length is 6″. There are 2 ‘chambers’. The inner steel pipe has a 0.40 inner diameter and 24 holes drilled in it.
This was a prototype, but dang did it work 😆 . The sharp report has been toned down to a deeper braaap. Much of the remaining noise is clearly the powerplant but I still think there is some more muzzle blast I can eliminate. I’m asking for advice on the top 1 or 2 improvements I can make to my design.
– Would a bigger outer PVC pipe (next size up is 1 1/4) give more room to bleed of pressure?
– would more (or larger) holes in my inner pipe help?
– I found some sweet nylon bushings that will replace my duct tape bushings so next rebuild I plan to create 3 chambers
I was pleasantly surprised to see the accuracy increased significantly 😮 !!! Not sure if this is due to increased pellet stabilization or simply weight at the end of the barrel. Opinions on this?
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Here it is – the final Scotchbrite wrappings are removed
The grey fitting in the bottom right slides snugly down over the barrel – I lucked out finding something that fit just right, both onto the barrel and also that fit inside the 1″ PVC. But I have since found other plumbing fittings that will go over 15 and 16mm barrels.
I used a cheesy dB meter app that runs on my iPad to measure the before/after. Oddly the dB reading was the same (~ 74 – 75) but it sure sounds much quieter to me. There is a louder, sharper crack when I fire it without the moderator and a deeper, more subdued report with it on.
Thanks!
My inner pipe is steel, 0.5″ OD and 0.4″ ID. I drilled 24 holes in it. At the center I used narrow wraps of duct tape to build up a bushing that centers it in the 1″ PVC pipe, thus creating a front and rear chamber.
The thing has worked great – quieted my springer significantly as well as increased accuracy. I am hesitant to fool with it but the tinkerer in me wants to improve on the cheesy duct tape I used for the prototype.
I am thinking of enlarging the center hole in three 1″ washers so I can weld them onto my center pipe to create 3 chambers. Should I drill holes in the washers to allow pressure to flow between the chambers?
Alternatively I have some fatter nylon bushings that fit but I would need to shim with one wrap of soda can aluminum and then use something like superglue to hold the bushing in place. I’m not sure how well superglue is going to work against that slick nylon.
All the threads here discuss baffles…I realize I’m using a different design but I have heard from others that the air from a springer is different than a PCP sop the design needs to be different. I don’t know how it should be different but I’m feeling good with the results I have achieved so far. I’m using wraps of 3M Scotchbrite pad in each chamber.
Hi!
I didn’t understand your exact configuration. So I’ll answer in general:
– Would a bigger outer PVC pipe (next size up is 1 1/4) give more room to bleed of pressure?
Naturally. More volume is better. I’ll go even 1 1/2 at that length.
– would more (or larger) holes in my inner pipe help?
Naturally. More turbulence is better. I’ll dump the tube and use small hair roller/curler. Even Weihrauach silencers use allmost similar inner parts = something like curlers and scotsbrite like material. And those silencers are effective.
– I found some sweet nylon bushings that will replace my duct tape bushings so next rebuild I plan to create 3 chambers
Weihrauach use 3 chambers. And surprice: 1’st and 3’dr chambers are equally sized. About 1/4 of total length. So in the midle chamber is 1/2 of total. That NOT suppose to be optimal structure. (1’st chamber should be the biggest.)
But at least below 40 fps Weihrauach is silent. Go figure….
C0man
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Not odd at all IMO.
That thing is not a silencer. It is a absorber. It cuts high parts of the sound and leave low parts flow frealy. (Google absorbtion muflers and chamber muflers and you’ll get the idea.)
High sound is more irritating than low to human. That is why it sounds better with it.
C0man