I have used Tipton plastic .22 LR snap caps, and they work well to a point. The firing pin is very sharp and the strike very hard. The rim of even these tough plastic caps is quickly damaged, and you have to rotate them.
A well-designed .22 revolver or pistol will not allow the firing pin to strike the chamber. The recess is cut deep enough that the pin does not strike the bottom, and the pin is shaped so that it does not strike outside the recess.
If the cylinder does not carry up properly, you will hit the cylinder and damage it, possibly the firing pin as well. That is another problem altogether, and not a safe situation with any revolver.
If everything is working properly, the main purpose of a snap cap is to reduce the stress on the firing pin itself, which is normally cushioned when it strikes the rim of a cartridge. That is true of any firearm, rim fire or center fire. I use snap caps when testing firearms after stripping or repairs, when no live ammunition should be within reach. The rims of .22 snap caps may be too weak be be extracted properly, especially after being driven into the chamber by the force of a dry fire. Aluminum center fire snap caps, with a plastic insert where the primer would go, work perfectly when tuning an action.