I could see this being the case, but it's got to be very narrow timing, and it probably only applies for the same type of action. A friend and I used to do a drill with his Glock 9mm. (After ensuring the gun was unloaded) one of us would point the pistol right at the other's head. The pointee would initiate action by grabbing the gun and the pointer would try to pull the trigger. It was impossible to pull the trigger…
If you intend to replicate your experiments in the future, you can explicitly seat a snap cap in the chamber and leave the magazine out (no mag safety on the Glock). That way you are still violating rules 2-4, but possibly not rule 1.