You are right, a pain to advertise air guns nowadays. Been thinking of selling some of mine as I near retirement - then I think maybe I'll have more time to use/fettle them. Mainly old BSA's/Webleys.
I usually keep a repeater CO2 near to the back door to scare off unwelcome visitors to the bird table & feeders. No, I don't shoot them! But keep an old metal tea tray underneath - the CLANG! scares the squizzers & magpies off a treat.