More .22 rim fire guns have been ruined by improper cleaning than ever wore out. Back before WWII, corrosive ammo (priming) made regular cleaning necessary. Having coached various small rifle & pistol teams for more than 50 years, I advise cleaning the bolt face and chamber area regularly to remove bullet lube build up but almost never poke anything down the barrels. Clean patch from the chamber end at the end of the season, maybe with a bit of rust preventative if the guns are going to be stored for several months. Rarely do .22 rim fire barrels develop serious leading that needs to be scrubbed away. I have a pair of BSA Martini .22s that are 100 years old and shoot good as new after untold 100,000's of rounds and no cleaning rod/bore brush down their barrels for 40 years on my watch.