Yes you absolutely "can" harm a barrel if your not carefull. But not being carefull and not cleaning it at all are two different things. As I siad,I have heard many people say not to clean a .22, but on the other hand, I have sen just as many shooters at the ranges, forums etc. saying just the opposite. I have been around firearms for the past 26+ years, and am always carefull when handling the weapon and do a proper cleaning of it. I am not saying "whos right" about the clean vs dirty issue.( every shooter has what works best for him or her) All I can say for a fact is "my personal" 15 22 shoots with better accuracy when having a clean barrel.
The last time I called S&W( to get my rifles MFG date) I asked them about this very issue. Turns out that S&W themselves told me I should clean the entire weapon after each outting, barrel included. I asked the S&W rep about this issue, of clean/dirty and possible damge if someone DOESNT take the proper precautions, and was told this basicly "It has a lifetime warranty, thats pretty much says it all huh?" I answered , the obvious" yep, pretty much" lol. Again not saying im right or your wrong, just my personal experiences with my 1522 is all. Happy new years guys!