While the Second Amendment provides a federal right to gun ownership, every single state has its own approach to legal gun use and safety. Being a responsible gun owner means having proper training and safe storage for any firearm you own. It also means complying with all applicable federal and state laws to protect yourself and others.
Missouri does not require any kind of permit for those who wish to purchase a rifle, shotgun or handgun in the state. There is also no requirement to register personal firearms. Those who own firearms in Missouri do not require any kind of license or a permit to carry their weapons.
While there are certain places you many not be able to carry a weapon, such as in certain restaurants, in general, it is legal to possess a firearm in any public space in Missouri. You can even conceal your handgun, so long as you are 19 years old or older or a member of the United States Armed Forces.
Open carry is also perfectly legal in Missouri, meaning that you can visually display a firearm in public. However, you can not display a weapon ready to be used in a manner that others find angry or threatening.
If you find yourself facing any kind of firearm charge in Missouri, the first thing you should do is familiarize yourself with state laws. After that, you may want to consider your options for a defense against the charges. Certain convictions could impact your ability to legally own firearms in the future, so a proactive response is likely in your best interests.
Source: NRA-ILA, "Missouri Gun Laws," accessed June 01, 2018