Muzzling the Leshiy - A Silencer Story

That is doable, however there would need to be a standardization of barrel length. In the video you linked, the so called "leshiy supertune" uses a 320mm barrel not a 300. This becomes more challenging and critical because there is no standardized spacer, like there is for the extended shroud, so the design would need to justify off the barrel muzzle itself, something the existing design doesn't do. All of this is certainly a possibility, but testing it to ensure proper function as well as optimizing it for sound attenuation would require the Leshiy itself. I hope all that made sense. 
 
Of course it makes sense :) 

I like Leshiy the way it was designed - short. Adding 350mm barrel makes the gun loose its proportions. Due to energy restrictions I use 12 ft/lbs Huma-Air regulator which gives ~85 shots in .22 and 65 shots in.177 - both on 250mm barrels. This is already championship of the world - so many shots out of such small cylinder. Not much to improve unless I change barrel to longer, 300mm (+20%) at least would be ok, and make it quiet at the same time. Using LW dia.12mm polygonal barrel will gain some air too as it is more efficient due to higher muzzle velocity.

The only thing is missing is the moderator insert designed for such ~300mm barrel. To make it more quiet there should be versions for .177/.22 and separately for .25. 
 
I have a couple of apologies to make. First is to STO for taking so long to actually write up my impressions of his work. Second is to all the folks following this thread, wondering "right, but how is it *really*?"
To STO - thank you. You are a gentleman and a scholar. I'm humbled by how much work you put into this, and how much data you share. Not to mention the knowledge that you share with this community of folks. 
So. 
My impressions.

Out of the box (and literally out of the shipping box), my first thought was - "damn, this thing is still loud". 
Then I reminded myself that I was comparing apples to bricks. I normally have my Leshiy set up with a Huma 12ft lbs reg, running at around 14-15 ft lbs. I'm originally a Brit, so 15 seems plenty, anymore an I run to my powder burners (which I'm giddy to have compared to the UK). 
Upon reflection, I realize that it's *much* quieter than it was stock, so I set about resetting to my personal baseline. 
My second thought on doing so was, "I must have changed the reg a bunch, as it's too quiet". Nope. Reg was the same, HS was in the same ballpark, I'm still pushing JSB 10.3's at around 830 fps. But darn, if this wasn't quiet. More than quiet, it had a nice tone. Which is, of course, completely subjective. But it just doesn't have the tinny twang or resonance that is common, just a very muted "thud". 

All in all, I'm extremely happy, and if STO decides to sell these commercially, I wouldn't hesitate to recommend one. It's a significant step up from the stock core, and quieter (IMO) than running other mods on top of something like the EagleVisionCam's adaptor, or DonnyFL's adaptor. If I could bring myself to drill holes in STO's core, I think I'd have the best of both worlds - hugely quieter than stock, at the stock length, with the option to add extra suppression if I wanted.

The TL;DR summary is - STO's core is terrific, and I'm happy to have been a part of this project. 
 
I'll add my two cents to this topic as well. To add complete transparency. STO's baffle is the only one I've tried but it is substantially quieter than stock. Less bark and overall noise.

Story time. We were shooting in a group family setting. I happened to have 2 in by go bag. One for my girlfriends Leshiy and a spare for a good friend that was also shooting a Leshiy. After switching my girlfriends stock baffle for the Sto. My friend decided he need one. After my friends wife (None shooter heard her's going off she also decided he need one). Surprise!!! We spend a lovely afternoon shooting off the deck carrying on a normal conversation.

Both were in .22 350mm shooting over 800fps. No point of impact change.

It definitely lived up to the title of the post

Dave