Just got off the phone with Richard, a gun-smith for CZ. I was curious about dry-firing my particular model, 452-Silhouette, and it turns out that all CZ rimfires have a lug-stop on their firing pin that impacts inside the bolt and stops the firing pin short of the breach face.
He still doesn't like to dry fire his own rimfires, though they have had to do it thousands of times at the factory, on test guns, and he has not seen it ruin any rifles so far.
I asked if he recommended snap caps for dry fire practice and he agree'd, though said re-using discharged rounds is fine as well, so long as you don't use them too many times and that you only use rounds discharged from your own gun, as discharged rounds reshape to the chamber they're fired from.
Hope this helps answer some questions others might have on this subject, I know it did for me.
Cheers,
bcode