SAFETY INSPECTION FOR THE CZ-52 PISTOL (prevent accidental discharge upon decocking on a live chamber)
The CZ-52 is a fascinating pistol design, chambered for the 7.62x25mm Tokarev round. If you dry-fire it, you're running a substantial risk of breaking the firing pin, and therefore the factory fitted them with a decocker. The problem is that, if the firing pin is a bit off, decocking a loaded weapon MAY result in an accidental discharge!
I'm not familiar with the procedure for correcting this, but I AM familiar with the procedure to check if your CZ-52's decocker happens to basically be an extra trigger. First, take your weapon TO A RANGE. Do not do this in your living room. You should take a loaded magazine (one round or eight, your call) and rack the slide to chamber a round as you would normally. Taking care to ensure that no part of your hand is behind the slide (you don't want broken fingers if it DOES go off) and that the weapon is pointed down-range, use the decocking lever. The hammer will slide forward, and your pistol will probably not go off. If it does, then you know never to decock a hot chamber. If it doesn't, then re-cock the hammer and decock it several more times, each time making sure to grip the weapon firmly and keep your cocking hand away from the rear of the slide. I recommend repeating this a minimum of ten times. If it doesn't fire in any of that, rack the slide to eject the round, and inspect the primer.
If the primer has been struck at all by the pin, you will see dents on the center of it. They may not be enough to touch off this round, but they might set off another. If the primer has not been struck AT ALL, then you can rest fairly well assured that it's safe to decock your CZ-52, but I would still make sure the chamber is empty and never decock on a live chamber.
Lastly, put the round you've been testing with back into the pistol and fire it downrange as you normally would. This is an important step, as you are verifying that the round wasn't a dud to begin with.
Another procedure, contributed by John of SKSboards:
Stick a #2 pencil (which happens to be approximately 30 caliber) down the barrel eraser-end first, and decock the pistol. If it moves, then you know the firing pin is making contact with it.