Help with ideas for baffle design for a very small moderator

[MrP]

I recently got some very small moderator housings from David (rocker1 at GTA). I’m trying to further quiet down a 22 empire XS that I recently acquired without adding much to the length. Just trying to get it quiet enough not to annoy my nice neighbors. The Empire XS has a short shroud with an air stripper and some space for the air to expand into, the question is what should come next

The smallest one has bout of 2” (52mm) of free space and a 22.2mm diameter. after the caps are threaded in. Two 26mm long baffles I had on hand fit perfectly, for example, and worked to deepen/soften the sound.

The longer can has 70mm of free space inside, same diameter.

The empty cans actually work reasonably well in themselves, but I wonder if there is some design that would make the best of this small space.

I have attached a picture of the empire xs with one of the short ones, and a pic of another similar one with a couple of baffles I had from an earlier purchase.

Any suggestions would be greatly appreciated

 

[EmptyTin_Tim]

linkBuck Rail has a cutaway view of his and his designs are night and day. Scroll to the bottom.

 

[rcs9250]

You did not mention if you have a 3D printer. I’m thinking maybe you do.
From what I have read through the years, changing the direction inside the can is what tames the report. I always wondered if a helical (spiral) insert/s that were alternating clockwise and counterclockwise a couple times in the available length would have an effect. Would be easy with a 3D printer, not so much with conventional machining.

 

[MrP]

Yes, I have a 3-D printer and I agree the helical idea is an interesting one. “Subscriber” at GTA (not sure of his handle here) cooked up a design that directs the air radially into specially contoured pockets to create smoke ring-like vortexes in each baffle.

Just like a smoke ring basically holds together as long as it keeps moving forward, the same thing is true in the baffles-as long as the air is flowing quickly those little vortexes spin up and hold air back until pressure or flow drops.

I’m doing my best to explain this - subscriber could describe it better since it’s his baby.

If there is no particular best approach I will probably try changing a few variables and see what happens.

 

[Vetmx]

The first step you take to having a quiet gun is not wasting air. Why do you think FX sends an empty can with with Impacts? When the gun is tuned properly, that’s all you need. On my XS, I vented the shroud, stopped the hammer bounce and even with power mods, the gun needed very little help to be backyard quiet. If you’re tuned too hot and along with the hammer bounce, the gun is going to be more difficult to silence.

 

[Joedirt199]

Paging @OldSpook, paging dr oldspook

 

[MrP]

The first step you take to having a quiet gun is not wasting air. Why do you think FX sends an empty can with with Impacts? When the gun is tuned properly, that’s all you need. On my XS, I vented the shroud, stopped the hammer bounce and even with power mods, the gun needed very little help to be backyard quiet. If you’re tuned too hot and along with the hammer bounce, the gun is going to be more difficult to silence.

I’ve shot it as set up from the factory (descending string so too much hammer).

I’ve been gradually backing off the hammer spring. I need to set up the chronograph to see what’s going on with the change.

I recognize the importance of efficient air use (for example a valve that shuts before the pellet exits the barrel). I will listen for hammer bounce. The spring stopper seems like a great idea but must be challenging to find the right spring and get it to perform.

 

[Vetmx]

If you can’t build a SSG, just use a short stiff spring. It’s almost as good. You’ll need a 2” long .48 OD .59” wire spring. Then bore your hammer to 1/2” to accept the spring. Boring it out will help reduce its weight. I also took even more weight off my hammer because they are just way too heavy. It’s like Kral builds their hammers to waste air.

 

[OldSpook]

You don't have enough volume there to do much. Put a couple conical baffles in there about 6 mm apart. Make the bore passage as close to caliber as you can get away with without clipping. Keep the exit hole really tight. That should give you 6 or 8 dBs of suppression. Then test for accuracy.