I shot 100 rounds of Eley Minor 9 124 grain with no malfunctions. It plunked when dropped into the barrel but would not fall out of the barrel without me giving the barrel a little shake.
This is a danger sign you need to pay attention to !
Typically, when you get those results the case is properly proportioned, but the OAL is too long for the CZ's short leade. The bullet is then wedging itself into the rifling, which is what's retaining the cartridge inside the chamber. This will typically defeat the "spin" portion of the "Plunk & Spin" test.
The danger is that if one of the cartridges happens to be 0.008 to 0.015" longer for any reason, then the slide does not go completely into battery. The trigger is allowed to drop the hammer, but the slide is not locked. Then you get accidents that look like this...

Of course, your Shadow may not be plastic, but the spewing of brass bits at 30,000 psi is never good for the human.