Tuning .22 or .25 Classic Leshiy for quiet tune?

Squirrel season is about over and I'm thinking about setting up one of my Classic Leshiys as a quiet backyard rabbit airgun.

I have the sub-12 reg and 22 and 25 barrels in both lengths, although I likely wont' be using my 25/350mm barrel for this application.

Shot count, trajectory and the compact nature of the 250mm barrel are not considerations in this case. Nor is the cost of the pellets as we have other plinking airguns. 

I do have Akula moderators in 22 and 25 cal. I also have the DonnyFL adapter for the 350mm barrel.

My pellet inventory makes me lean towards using the 25 cal, 250mm barrel for this. And I also think it would be more quiet than the 22, if shooting at higher power levels is any indication. 

But shooting 25 grain pellets at power levels similar to my current rabbit airgun (P-rod) means awfully slow speeds, which makes me concerned about rabbits flinching.

Makes me wonder if the 22/350mm barrel isn't a better starting point for this?

Appreciate any input.




 
So, the longer barrel (more volume) will allow for more expansion, and lower report.

Honestly any of these at low power should be VERY quiet with any decent moderator.

Most of your noise is going to be projectile impact downrange. And I'm honestly not sure, but I think the .25 might end up being quieter? Mine at about 28fpe has been pretty quiet on impact when taking grey squirrel. But this is not anywhere close to 12fpe 
 
So, the longer barrel (more volume) will allow for more expansion, and lower report.

Honestly any of these at low power should be VERY quiet with any decent moderator.

Most of your noise is going to be projectile impact downrange. And I'm honestly not sure, but I think the .25 might end up being quieter? Mine at about 28fpe has been pretty quiet on impact when taking grey squirrel. But this is not anywhere close to 12fpe

I'm not certain about impact noise either. 

I should set up a duct seal trap outside & have my son shoot it from a slightly open window with a few different options & see if I can tell a difference.


 
I found the .25 H&N Field&Target 19gr pellets work really well in the 350mm barrel. Reg set at ~110bar the velocity is in the 860fps. Very quiet with the DonnyFL V2 baffle with the top of the baffle stuffed with Scrub Sponge Scouring Pads. Not your run or the mill "felt", but a million little pockets to trap air. You could probably take a few clicks off the hammer spring and get down to ~800fps.

This is what they look like.. https://www.amazon.com/gp/product/B0768JLFR2/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

The STO baffle is really quiet, too. Way more quiet than the stock Edgun baffle and the same size so it could be used with either the 250mm or 350mm barrel.