I beg to differ, this may be contrary to the old hunting dogma about the 22lr, but here goes. Take it from someone out of a whole family of smallbore rifle competitors, clean that 22 after EVERY shooting session. After a hunting outing where you only shoot a few rounds its not that important, but when you shoot a whole bunch at the range or plinking this is what happens.
Every time you fire a round a little bit of molten silica (from the primer) drops out of the case, just in front of it. It builds up a little as you continue to shoot, but stays soft during a shooting session. When you are done and as the rifle cools over the next several hours this little "smiley" (it looks like a smiley face if you look down the barrel from the breach end) hardens into kind of a glass. Once it is hardened it is very dificult to remove because it has bonded to the steel. The next time you go out to shoot, the first couple rounds tear this "smiley" out of the barrel, taking a few microns of steel with it. If you repeat this process the smiley becomes a ring. And then it starts another smiley ahead of that one, and so on.
These rings will absolutely ruin accuracy. Quite a few years ago we looked at the club rifles at our local range that had quit shooting well and had been set aside. Some of these rifles had 5 or 6 of these rings just ahead of the chamber. A gunsmith who was also a member of the club took the rifles and set the barrels back about an inch and rechambered them. Voiala! They went back to shooting like the were new again.
As far as I know, this phenomenon is unique to rimfires due to the priming compound they use. And like I said during a shooting session or match you don't need to clean it (unless powder fouling is affecting the accuracy) because it is kept soft by the following rounds keeping the barrel warm. My brother has an Anshutz that he won the state junior championship with. He bought it from a previous state junior champion, who bought if from another state junior champion. I got into shooting more after college and started shooting that rifle in competition as well. We figure that rifle has had a quarter to a half million rounds through it. It shoots just as good now as it ever did because it has been cleaned after EVERY time its been shot.