There are no licensed firearms. MO doesn't have a license for you to have a gun.

One of the court cases still making it's way is that MO is one of the only states that punishes local law enforcement for doing the work of federal police. Federal police can still operate but they cannot use local law enforcement to enact their work.

The DOJ doesn't like that, despite it becoming a law. Because of this and the liability that officers face personally as well as the department, a lot of the 'federal only' things have effectively stopped being enforced.

The one caveat I would say to this is that in Mark Twain national forest and other national forests, park rangers have law enforcement abilities and you are on federal land. A joint and a gun walking around a federal park, any federal park, will not end well if you're caught.

As for just going about your day, since ATF or FBI or DEA aren't likely to be around, you're probably okay but it really depends on the location and police force.

It is still a felony to be in possession of controlled substances and a firearm at the same time.