Just received a 500 mm fx barrel, noticed a small hole on the receiver end, now I know what it’s for…. Thanks
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Holes in a shroud
- Thread starter aldea6
- Start date
Much testing has taught me that a single 1/8” hole drilled in the shroud near the breech with no less than 4 wads cut from a Mr Clean cleaning pad to slide over the bbl and rest at the breech is perfect. This will relieve shroud pressure enough to enhance sound reduction while preventing sound transfer to escape at the breech end of the gun. Accuracy is not affected.
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I have only 3 pcps but I've played with them all to get lower sound. I have all three in the low 80s to high 70 db level at 15 feet in front of the muzzle. Two now have vented shrouds. My P35 came that way and I added them to my Avenger. Both have a little puff of air coming out when a shot is fired. If my hand is nearby I feel it.
My Prod came with nothing in the shroud but was only about 85 db - I think that is a very reasonable definition of backyard friendly. It is about the level of the noise from a pellet hitting a paper target. (If you are testing moderators you may want to keep this in mind - you may want to place the pellet a hundred yards or more away to be sure it is not the pellet impact your meter sees) I currently wears a Buck Rail moderator and is about 10 db quieter - and also more accurate.
I played with home made moderators for my Avenger and got one that worked but I had to unscrew it to fill the gun and after doing that repeatedly, it started clipping. So I switched to a Tanto and it was about 86 db (at 15 feet). Then I got a couple printed moderators. One is short and fits fully within the shroud. The other is about 3 inches longer. Surprisingly the shorter one is quieter - about 82 db. I also tried to make baffles for the Avenger before getting the Tanto and drilled the back of the shroud while I was messing with baffles and hair curlers. They didn't work. So I don't really know if they are helping measurably or not. If I wanted to know, I would tape over them and measure the sound level.
My P35 shroud came with 7 thin aluminum baffles in the shroud ahead of the barrel. It was about 85 db. Then I saw a video by Aaron Cantrell saying pulling some baffles and putting in felt wrapped hair curlers made his P15s quieter. I was skeptical but I tried it and it works. I currently have a half curler w/baffle followed by a full curler with baffle in the shroud and my most recent measurements were just under 80 db. I've measured as low as 75 db or so initially so I don't know if the felt is loading up with pellet dust and making the shroud a little less effective or what. My shroud is slid forward about 1/2 inch to accomidate the baffle/curlers.
When I was making my own moderators I tried poking holes in the outside and never saw a benefit. It seems like there should be one like there should for venting the shroud since it is reducing pressure. But my limited experience is that things that should make a gun quieter don't always seem to. If you keep them small and limited in number I don't think it hurts.
My Prod came with nothing in the shroud but was only about 85 db - I think that is a very reasonable definition of backyard friendly. It is about the level of the noise from a pellet hitting a paper target. (If you are testing moderators you may want to keep this in mind - you may want to place the pellet a hundred yards or more away to be sure it is not the pellet impact your meter sees) I currently wears a Buck Rail moderator and is about 10 db quieter - and also more accurate.
I played with home made moderators for my Avenger and got one that worked but I had to unscrew it to fill the gun and after doing that repeatedly, it started clipping. So I switched to a Tanto and it was about 86 db (at 15 feet). Then I got a couple printed moderators. One is short and fits fully within the shroud. The other is about 3 inches longer. Surprisingly the shorter one is quieter - about 82 db. I also tried to make baffles for the Avenger before getting the Tanto and drilled the back of the shroud while I was messing with baffles and hair curlers. They didn't work. So I don't really know if they are helping measurably or not. If I wanted to know, I would tape over them and measure the sound level.
My P35 shroud came with 7 thin aluminum baffles in the shroud ahead of the barrel. It was about 85 db. Then I saw a video by Aaron Cantrell saying pulling some baffles and putting in felt wrapped hair curlers made his P15s quieter. I was skeptical but I tried it and it works. I currently have a half curler w/baffle followed by a full curler with baffle in the shroud and my most recent measurements were just under 80 db. I've measured as low as 75 db or so initially so I don't know if the felt is loading up with pellet dust and making the shroud a little less effective or what. My shroud is slid forward about 1/2 inch to accomidate the baffle/curlers.
When I was making my own moderators I tried poking holes in the outside and never saw a benefit. It seems like there should be one like there should for venting the shroud since it is reducing pressure. But my limited experience is that things that should make a gun quieter don't always seem to. If you keep them small and limited in number I don't think it hurts.
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Vent holes came on both my Reximex Throne genII and SPA P35. They being both bullpups and my ears right next to the vent holes, the loud pops annoyed the hell out of me. I made a new shroud for the P35 and plugged the holes on the Throne with some tubing. I don't know if venting helps any but it sure makes shooting more pleasant not having them.
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