The 2 sections we are concerned with, for concealed carriers in Missouri, are RMS 571.0 and 563.0. These cover the gun laws and use of force laws in defense of self, property and others.
missouri handgun laws This link is to a pdf and checked for safety.
For a summary of gun laws in other states check out NRA-ILA State Gun Laws.
Another source is www.handgunlaw.us/“>www.handgunlaw.us/
There is a handy book, “Traveler’s Guide to the Firearm Laws of the Fifty States“, by J.Scott Kappas, Esq., that is available for purchase and updated regularly and is great for researching the state laws of places where you are travelling to or through. Since you are responsible for complying with the laws of each state you possess your gun in, including airline layovers.