It's not usually a good idea to dry fire a rimfire, that being said you shouldn't store the gun with the internal spring compressed, so once you're done cleaning it or whatever you're doing with an empty mag inserted in the pistol you can dry fire it to store away.
I'm not conflicting with the previous opinion/statement. 22's should not be dry fired as much as possible. However ruger says that with the mag in the gun it dosent damage it, you obviously have to dry fire it to store it properly so all manufacturer take that into consideration. You're not going to break your pistol from dry firing it a few times but it does cause extra stress and wear on your action.
The reason Ruger says the mag. has to be in the gun is because the gun will not function without the mag in the gun. Has nothing to do with dry fire damage. I don't know of any modern handguns that can.t be dry fired.
In revolvers I use fired brass sometimes, because its easy to do. Semi autos as in modern guns, when I dry fire I don,t worry about it. Some of the old guns, and cheap guns, had a problem. If ruger says its OK, have at it. Most of my trigger time is with real ammo. 95,000 shells in the last two years. Who needs to dry fire?
I just bought a SR less than a week ago, and I love it. 1500 rounds already.
I have two SR22s, one is over four years old and has been dry fired over 5,000 times (probably more) and over 7,000 rounds including a 1,000 round "torture test". One failure to fire (Remington ammo) and one failure to go fully into battery after round 757. It will eat any ammo I put in the magazine, although CCI quiet won't cycle the slide (not that I would expect it to). Excellent teaching pistol in my opinion.
The way the chamber on the SR22 is designed ensures that the firing pin does not hit the metal face of the breach. It will only strike the rim of a cartridge and not make it to the breach face on an empty chamber. So by all means, dry fire away.
As for needing to "dry fire it to store it properly", no. This is a hammer fired weapon, not striker fired, so dropping the hammer is all that is needed for proper storage. In fact, Ruger even included a safety/decocker lever to make doing this even more simple.