Welcome to Missouri. Like some have mentioned, there are a few public ranges that do not have range officials at them. The closet one to the base is in Concordia (About 13 miles if I remember correctly).
I have heard good things about the Sedalia Club. Higginsville has a big out door range for the gun club members there. They do the cowboy shooting also. (At one time I had heard talk of them doing the costume shooting from the roaring 20's, but I do not know if it ever came to fruition.)
When you get here and get set up, give me a PM. I have a small range for pistols and rifles (Max 100 yards) set up. If you promise not to tell anyone what a lousy shot I am, I'll invite you up.
I am 14 miles from the base.
For long distance shoots (450 - 1000 yards) there is a group around Holden Missouri. They get together at a farm out there and have fun.
Shooting supplies, depending on what you are looking for, are available at the BX, A couple of places here in Warrensburg, Sedalia, Independence has a Bass Pro and a little further is a cabelas. Outside of St. Louis and Kansas City, most of Missouri is a very gun friendly state.