Old Turner used to give some of the up and coming builders work when they didn't have guns on the books. I don't know about Southgate, but, he had Jack Garner build a guns from Dixie kits. By the way Turners idea of a kit, back then, was nothing like what we call a kit today. They here basically wood, and parts, and instructions.
Southgate did use quite a few of those F1 flintlocks turner imported.
Hungry Horse