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Silencer Noob – What Is Required Reading for a DIY Shroud for an Air Pistol?
Posted: Wed Dec 18, 2019 4:14 pm
Hi from way down South --
from Peru -- where there are no crazy silencer laws and airgun restrictions....
I’m a silencer noob. What is required reading for a DIY shroud?
I’m looking for quieting down a very low powered PCP without adding much length,
maybe an inch or two beyond the muzzle at the most.
Because of the airtube being really close to the barrel I'm very open to an asymmetrical design (Leshiy-type).
Or even a "rectangular silencer box" if necessary (yes, at that suggestion I can see the silencer junkies roll their eyes
in shocked disbelief, and I do admit, it would look pretty hideous, but hey, let's see the options...!).
Thanks for your help!
Re: Silencer Noob – What Is Required Reading for a DIY Shroud for an Air Pistol?
Posted: Wed Dec 18, 2019 6:28 pm
I have one competition type air pistol which offers only about 1mm clearance between the air cylinder and the barrel, so not much clearance for a tube, and if it was to be suppressed for use on rats (avoiding disturbing neighbours at night) this would require an asymmetrical solution. Further increasing difficulty were the 3 small ports along the top of the barrel, there to provide some downwards force to minimize muzzle flip - along with the tungsten sliding weight behind the bolt, powered by a controlled amount of the air released on firing, which in combination make the pistol essentially free of recoil. I needed to shroud the barrel to quiet the noise from these ports, and though muzzle velocity with an 8.3gr pellet was only about 500fps, there was also some noise to be removed at the muzzle.
My solution started with a piece of 1" square aluminum tubing about 35cm long, slipped over the barrel after shaving down the middle of one face to about 0.7mm thickness. This was 8cm longer than the exposed barrel section. The bottom of the aluminum muzzle brake being flat, it controlled tilt of the tube at the front. At the back I made two low-friction plastic plugs about 1cm deep with half-rounds cut such that when pushed together they sealed against the barrel and sealed the back of the square tube with a slight taper fit. Pushing the tube against this plug closed the back of the tube, while a single plastic plug fitted around the upper and side portions of the muzzle brake kept that stable. This took care of the anti-flip ports along the top of the barrel.
With the remaining 8cm of tube I made a plastic end cap, held in with set screws, filling the space between muzzle and cap with an array of little V shaped baffles soldered together out of very thin sheet steel - pellet tins cut up and bent to shape. As such I built what is essentially a square monocore baffle stack, 8 little curving V baffles with small gaps between, then bored a 0.23" hole through it in the correct location to clear pellets. The end cap is also profiled as a sort of baffle.
Once assembled, this is such a quiet PCP pistol that I have had people walking their dogs within several metres of my yard when I shoot a rat and even the dog does not notice. The noise is perhaps similar to cracking a roasted peanut shell, the impact on the rat being somewhat louder. I use a small non-magnifying thermal scope lately, but an infrared setup mounted behind a 4x scope is actually more accurate, just a lot more cumbersome. The thermal offers the advantage of being invisible to rats, where the dull red of an infrared emitter alarms them, typically giving me only a very brief shot window.
The Leshiy's baffles seem not very efficient. I suspect it is quite quiet because of good tuning between the valve and regulated pressure, matching well to the barrel length, leaving little work for a suppressor. Then of course there is the very large volume of the Leshiy suppressor. I've shot one unsuppressed (Canadian version) and it wasn't terribly loud, shooting at about 25fpe in .22", but by no means back yard friendly. Neighbours would certainly be alarmed.