Revolvers are considerably safer than Semi-Automatics. You can readily determine if they are loaded. Also if not a 'hammerless' they are not likely to fire when picked up if your trigger finger does not engage the trigger. If is is lying on the table and the hammer is back ? Definitely unsafe. A semi-auto unless it is a 1911 may or may not be safe. Some semi's have an indicator atop the slide to let you know they are loaded with a round in the chamber. A 1911 is relatively safe if the hammer is not 'cocked'. To handle any semi-auto the safest thing is to remove the magazine and then clear the pistol of a loaded round. Frankly I have tremendous respect to a semi-auto. You have to be very aware and alert when handling them, never careless. Never pull the slide back if you have not removed the magazine. Otherwise you just 'cocked' it and/or racked a round into the chamber if none was there before.This is true with any semi-automatic pistol. You can never be too careful.