I've just realised the key to making really quiet PCP/CO2 airguns....

[Black Beard]

Have a gun which works on a small quantity of high pressure air rather than a larger quantity of lower pressure. That means that when it expands and exits the barrel it will be at a lower pressure.

Use heavy pellets so they take more energy out of the air.

Use a .25. The air will be at a lower pressure when it exits as it has filled the larger barrel. .25s rock.

All this assumes 12ftlb energy output.

Or just detune to 6ftlb- so you need less air in the first place.

[les allam]

Turning my earing aid off Usally works for me.
Les..

[Captain Bongo]

Have a gun which works on a small quantity of high pressure air rather than a larger quantity of lower pressure. That means that when it expands and exits the barrel it will be at a lower pressure.

Exactly this (In my humble opinion). Regulation before moderation.

[tinbum]

Regulation before moderation.

I've been trying to find a new motto, that's perfect!

Now, how does it apply to wine........

[rapidresponse1]

as tony has said

[Antoni]

I was a member of a full-bore pistol club 25 years ago. Some-one brought a .22 rimfire rifle to the range. I was amazed at how quiet it was. No silencer fitted. It made much less noise than my springer rifle. Many folks on here will be aware of that but many folks might be surprised.

All about where and when the peak pressure is I suppose.

[xbow]

On 10m PCP’s the barrel proper is fitted inside a much longer tube. Manufacturers claimed it was advantageous for accuracy for the pellet to enter “still” air when it exited the barrel. The tube is also needed though to maintain a suitable sight radius. If you turn a drilled plastic plug with a cone on the end and insert this inside the tube it quietens them quite a bit. I made the plug from red plastic so it was easily visible. It had two O rings fitted to keep it in the barrel and the end was threaded M8 a little way so a bolt could be inserted to remove it if required.

[u.k.neil]

On 10m PCP’s the barrel proper is fitted inside a much longer tube. Manufacturers claimed it was advantageous for accuracy for the pellet to enter “still” air when it exited the barrel. The tube is also needed though to maintain a suitable sight radius. If you turn a drilled plastic plug with a cone on the end and insert this inside the tube it quietens them quite a bit. I made the plug from red plastic so it was easily visible. It had two O rings fitted to keep it in the barrel and the end was threaded M8 a little way so a bolt could be inserted to remove it if required.

I did this many years ago on the FWP 600 SSP series and the newer 700 and 800 series and it almost made them silent.


Neil

[Shed tuner]

all very much on the right track (except for the ultra stealthy suggestion )

this month I've mostly been fitting SSGs (stopping spring guides) which do exactly as you say.. by reducing multiple secondary valve strikes, the only air used is that which is required to usefully propell the pellet to the desired velocity. they sound snappier and crisper unmoderated, especially the "fart noise" co2 guns, but with a mod in place it's just a vast improvement.

ive had to use a variety of approaches, in increasing order of difficulty:
theoben rapid - extending into a void within the front of the hammer so simple
smk co2 rabit destroyer* - through the rear cap via an existing hole extending into a ready made void in the stock, also damn simple
ratcatcher - through the hammer a little tricky
kral - telescopic spring guide (really quite tricky due to very limited space)

the crispness of the firing cyle, and the sound reduction on all of these is really impressive....

Apparently SSGs work really well in harmony the regulators too, but Im a bit luke warm on regs due to reliability issues.. i might stick a huma or lane reg in the kral though. in contrast that's the beaty of SSGs.. there's really very little to go wrong.

oh, and for sure longer barrels help too, but diminishing returns over about 16 inches, although CO2 does like a bit more..

HTH JB

* a much better designed gun than the ratcatcher for less money and you get a metal receiver with dovetails as standard, and a nice fat bolt, a decent diameter barrel, and a proper stock.