OK, you want an explanation so here goes.
You should not dry fire .22 rimfire. As stated above it can damage the firing pin & the chamber face where it hits.
On old revolvers that have the firing pin attached to the hammer it's a bad idea to dry fire. When the hammer falls, the firing pin fits in a hole to strike the primer. If there is nothing to strike the firing pin can get lodged in the hole or widen the hole or the firing pin can be sheared along its sides.
Now, I'll tell you that my Ruger SR9 says that you should not dry fire the gun without a magazine in the gun.
I was told by Ruger that it can damage the magazine safety if you fire it without a magazine in the gun. So since I removed the mag safety I don't worry about this.
I was also told that it can damage the firing pin from overtravel without a magazine in the gun. I was a bit confused by this & got no real explanation but was told that if I used a snap cap I would be OK. I'm not going to worry about it when I just check for function right after cleaning the gun but if I am going to dry fire for practice I will throw a snap cap in.
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