The forensic technician describes the handgun found at the crime to Logan and Ceretta. There's no reason for her to do this as they were at the crime and almost discovered the weapon or saw it. as it was being processed for evidence.
When the ballistics expert demonstrated to Ceretta and Logan the difference between a single action and double action pistol, they all violated the first rule of gun safety: ALWAYS treat every firearm as if it is loaded UNTIL you have confirmed for YOURSELF that it isn't, NEVER assume a gun is unloaded; this is something that is drilled into law enforcement during basic training. The forensics tech picks the gun up, cocks the hammer and pulls the trigger, without double checking (for Ceretta & Logan's benefit) to make sure it wasn't loaded. When Logan picked up the double action, he also pulled the trigger without checking to see if its loaded, he assumed that the tech had made sure it wasn't loaded, which can prove to be a fatal mistake. Failing to heed this rule is how Alec Baldwin accidentally shot and killed cinematographer Halyna Hutchins, and seriously injured director Joel Souza, on the set of Rust (2024) and led to Baldwin & set armorer Hannah Gutierrez-Reed being charged with involuntary manslaughter.