22 shot shells will not harm the barrel. You need to be very close to your target if you are using a rifled barrel 22, because the rifling causes the shot pattern to spread open fast as it leaves the barrel (and there's not that much shot to begin with for good pattern density). So the closer the better (10 feet). If you have a smooth bore 22, the pattern will stay more together, but still the effective range should remain kind'a close, say about 15 feet, because there's not that much shot in the round.
Some 22 shot shells have long brass that is crimped at the top to hold in the shot. They can jam sometimes in a gun upon ejecting, as the brass is just a little too long. Shot shells that have plastic cups at the end to hold in the shot are the proper length and will not be too long to cause a jam. If I remember correctly, those were made by CCI?
Years ago the gun companies made 22 rifles with the option of a smooth bore barrel for 22 shot shells. They were intended for small varmint control in a garden, and I think there used to be a sport for shooting small clay targets indoors of large buildings?
Those 22 smooth bore guns are worth big dollars today, mostly as a collectable. As far as I know, no companies are making a 22 smooth bore today.