I treat it as tools, so I'm not buying anything that doesn't fill a precise job. And as a matter a fact I haven't changed anything in over 30 years.
Where we live, peoples go air powered or Co2 for these. You have to be extremely cautious, in many occasions you can't take the shot. Too many things behind them. But when a squirrel has the idea to make his nest in your recycle bin, There's no other way. They come back and make new holes to get in each time they're fixed.
So I used an old Crossman American Classic 22, That I played with for a couple months. Replaced the stock, the barrel, the pump and polished the trigger to 1 pound click. Replaced the barrel supports added 2 picatinny rails, Some good telescope, a tripod and zeroed it parallel to the canon.
It looks dead pan tactical loll, I call it "The Squirrelator"...
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They are really fun to mod.