St. Louis Branch | Master Halco contact@masterhalco.com. About the Branch. Branch Manager Doug Stonebarger. Location: 420 North Dr, St Charles, MO 63301. Branch Phone: (636) 946-3222 Branch Email: Sales-StLouis@MasterHalco.com Hours contact@masterhalco.com. About the Branch. Branch Manager Doug Stonebarger. Location: 420 North Dr, St Charles, MO 63301. Branch Phone: (636) 946-3222 Branch Email: Sales-StLouis@MasterHalco.com Hours: 7:30 - 4:30, Monday - Friday Services Offered - Will Call - Delivery to Customer - Delivery to Jobsite