webley-fosbery automatic revolver
The Webley–Fosbery Self-Cocking Automatic Revolver was an unusual, recoil-operated, automatic revolver designed by Lieutenant Colonel George Vincent Fosbery, VC and produced by the Webley & Scott company from 1901 to 1924. The revolver is easily recognisable by the zig-zag grooves on the cylinder.
This tag implicates revolver (learn more).