Thank you but it is not as much about the money as it is the noise.
A .22 rifle with the right ammo will generate much less noise than a high-powered pellet gun. This is due to the enormous expansion ratio you get when firing a .22 Short (not HV) through a long barrel. The case has a small volume compared to the volume of the bore. When the bullet gets to the muzzle, the gas has expanded so much the the residual pressure is very low. With subsonic ammo, it's the muzzle blast that makes the noise.
A spring-piston airgun that's powerful enough for hunting has a large gas cylinder, many times larger in volume than a .22 Short case. This means that the pressure is maintained as the pellet goes down the bore. The residual pressure is still fairly high when the pellet exits the muzzle so they are fairly noisy, but still not as powerful as a .22 Short.
Spend a little more and you can get a .22 repeater that fires shorts.
Don't need the long barrel except it is quieter than a 6" revolver.
How are the subsonic 22s in a 6" revolver?
They will be surprisingly loud from a pistol, much much quieter from a rifle due to the increased expansion ratio.
I grew up in PA and shot a fair number of groundhogs with a .22 LR, but I honestly don't think there is a really quiet round that is powerful enough that one shot will do the critters in, even with a head shot.
Yes, they can take 4-5 hits to the body with a .22 LR to stop them. On the other hand, I've dropped them cold with a Beeman .22 pellet gun from 25 yards or so. Accuracy is key, no pellet gun has enough power for center of mass shots. I've also dispatched hundreds of trapped groundhogs, racoons, opossum, feral cats and similar sized animals with the Standard Velocity .22 Short round; it's %100 effective with proper shot placement.
Those CB caps and Colibri's out of a long barreled rifle is what you want.
They're extremely quiet, but they're not accurate.
If youre seriously thinking of the traps, you dont want the leg hold, you want a Conibear type body grip trap.
For groundhog, you would need a Conibear 220, the 110 shown wouldn't be humane or effective. Those are serious killer traps; I wouln't recommend them for a beginner, or for use anywhere around a house where you could catch a nosy dog, etc... If you catch the wrong thing with the Soft Catch trap, just let it go and no harm done.
The Soft Catch works fine in a hole set if you make a depression within the hole. This is to make sure their stumpy little leg will be extended when they step in it.