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biador619 · New Member

Hi. I own a nitro venom dusk. So far I put around thirty rounds through her. I couldn't stand the loud sound from firing off a pellet so I made a muffler. I got a 1/2" PVC pipe and drilled it full of holes, covered it tightly with cotton, inserted it into a 1.5" PVC pipe and put end caps on it. It helped drop the DB from 103 to 91. Not bad but it's still loud. I did some reading and people were saying that the majority of the sound produced from the nitro piston rifle is from the piston itself. So I tested this theory. I tested by shoving the end of the barrel between a thick blanket and guess what....the DB read at only 55 DB. crazy right. There was barely any noise from the actual piston. Now this got me wondering how I can muffle the sound even more. Should I just stick with the current muffler I have now and just replace the cotton with a different type of material? Or should I just use a 1.5" PVC and use baffles? The muffler lol is about 8" already and I don't want it any longer. Any thoughts?[/b]

Alstone · Moderator & Site Supporter

To really get the sound down you need a tube 8” long and 1.5” dia, use large dia washers to split it into four sections, in each section use a hair roller wrapped in a strip of scotch bright pad, this should bring the sound down to around 65-70 db at 10 meters.

The key to mufflers is volume the more the better, just be careful using or owning one in the USA, as their are very draconian penalties’ if you do not have a licence for it.

Al

biador619 · New Member

Alright I'll give this a shot. Does scotchbrite really work better than cotton? Also will making the exit hole of the muffler the smallest size possibly lower the DB much more? Hoping ill be a to drop the DB down to 60db or less. Oh another question will adding more sections lower the DB even more? Thanks

Alstone · Moderator & Site Supporter

Cotton is to dense and will compress, reducing the exit hole will not make much difference, as you should have reduced the pressure considerably by the time the pellet reaches that point, plus if you cut the clearance down to much it will interfere with the pellet flight.

Increasing the volume makes a lot of difference, increase the tube dia to 2” and length to 9”, and it should be very quiet. You don’t say what cal the rifle is, but a .22 running around 12 flb will be quieter than a .177 at the same power.

Al

biador619 · New Member

Well I tried exactly what you suggested but the DB is still at 90 ish DB. I used scotch brite, hair rollers and a 1.5"x8" PVC. I also used 5 1/2" washers between the segments. This is pretty frustrating :/ is it probably the hight velocity of my .177 7g pellets? Should I go with a heavier pellet to get a slower velocity?

garththomas · Veteran Member

Did you have someone else stand back and listen. a lot of the noise comes from the spring action even with a gas spring.

biador619 · New Member

No I didn't didn't have anyone with me. The nitro piston itself just make a tiny thump. All the noise is being generated at the muzzle. I'll post another update once I do some test shots with a heavier pellet.

toadmyster223 · Senior Member

Your pellets aren't going fast enough to crack a sonic boom, are they? I haven't shot a Nitro 177, I don't know if they will do that with standard ammo. If you're using special Gamo gold ammo or something, I'd stop

biador619 · New Member

For now I'm just using the crosman premier hollow points @7.9g I just going by, the heavier pellet the harder the impact along with lower velocity. And with lower velocity I'm hoping the sound at the end of the barrel will be much less. I think it's the only option left unless I cans find a better way to build a muffler. I don't think I'm breaking the sound barrier but I think the exiting pressure of 900-1000 FPS will still create a lot of noise.

Alstone · Moderator & Site Supporter

The hole in the washers you are using to divide the chambers up need to have around a 5.5-6mm hole, the chambers should be divided with the first being one third of the muffler length, and the rest equally spread over the remaining length.

To secure the baffles make them a good fit in the outer tube and use a smaller tube sections between to hold them in place, a good seal and solid construction makes a lot of difference, and all joints being gas tight.

Al

radar · Silver Status Member

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Mark5043 · Silver Status Member