We recently spotted rats on our bird feeder and climbing the plum tree, so I ordered a couple of rat traps from eBay (the spring type). When they caught a couple still alive trapped by their legs, I dug out my
45-year old BSA Meteor .22 air rifle to dispatch them, but a couple of test shots into some wood barely made a dent, so the club hammer had to do.Then I had a closer look at the gun which hadn't been out of its case for many years. On disassembly the problems were obvious. The piston O-ring had perished, the cork breech seal had crumbled away and the main spring had compressed by several inches. At least that made getting it out a doddle, compared to getting the new one in.
Anyway, that was a most satisfying D-I-Y job. Pellets now easily go through 18mm chipboard and I can't wait to catch some more rats.