She's ignorant as hell. No matter how many times someone explains the nature of semi-auto firearms to her, she continues to think "pull and hold trigger = weapon fires continuously."
In some respects, Whoopi is even worse. She claims to own guns but is mystified by the idea of hunting with an AR. On many occasions, she's suggested that the AD has so much firepower, if one used the weapon to shoot a deer, "only the tail might be leff behint!"
It's a rifle, Guinan, not a bazooka or fucking phaser set to vaporize :/