wildcatter

noun3

1. •
   (US) Someone who drills for oil speculatively.
2. •
   A worker who participates in a wildcat strike.
3. •
   A person who makes wildcat cartridges and the guns that use them.

   • Roy Weatherby began his career in the firearms industry as a “wildcatter”, developing his revolutionary ideas about rifle cartridge performance and design. — 2005