Lots of Hog wash in this thread. From both sides, the hoplophoics and guys thinking they know gun laws. ( Just tryin to be fair its a fairly recent change in MO. law.)
571.030. 1. A person commits the crime of unlawful use of weapons if he or she knowingly:
(5) Has a firearm or projectile weapon readily capable of lethal use on his or her person, while he or she is intoxicated, and handles or otherwise uses such firearm or projectile weapon in either a negligent or unlawful manner or discharges such firearm or projectile weapon unless acting in self-defense;
Found Here: http://www.moga.mo.gov/statutes/C500-599/5710000030.HTM
So drunk with gun while not smart for stupid drunks, is not aginst the law anymore. But drunk with gun and do something stupid/illegal with it is well illegal.