Well, I'll give this a shot. Others can correct me if I'm wrong about something or add any details that I might miss.
I live in St. Charles County and purchased my first pistol back in February. It has recently come to my attention that the County Sheriff's office has moved since then. Back in February, the sheriff's office was on Second Street in Old Town St. Charles, but I've heard that it's moved out to O'Fallon near TR Hughes and Tom Ginnever Dr. (near where the Rascals play). According to the St. Charles County website (
www.saintcharlescounty.org/DesktopDefault.aspx?tabid=193), here's the new address:
County Sheriff's Department
101 Crossing Industrial Ct.
O' Fallon, MO 63366
To obtain a permit, go to the St. Charles County Sheriff's office and tell you want an application for a permit to perchase a pistol. Then, just fill out the form. You'll need 2 proofs of residence in St. Charles County. I'm pretty sure one must be a photo ID (i.e. Driver's license, passport). The other can be a utility bill or a voter registration card. There is also a $10 (I think) fee. After completing the form, they verify your residence, and take your money. If all is well, they give you a card that tells you when you can come back to pick up your permit to purchase a pistol (7 business days, I think). I believe the permit to purchase is then good for 30 days. Take the permit to the gun store and buy pistol. The gun store will then fill in info about the pistol you purchased and return the form to St. Charles County. You also get a copy to keep.
I think that should cover it. Others can add details I missed or correct any of this that is incorrect. Hope this helps.