U.S. MARK IV 1-7/16″ 37mm Flare Pistol
| 01. Original name | Mk IV Signal Pistol | |
| 02. Other official names | MARK IV 1 7/16″ | |
| 03. Popular names | Harrington & Richardson Mark IV | |
| 04. Chamberings | 37mm (1 7/16″) | |
| 05. Designed by | Harrington & Richardson | |
| 06. Design date | ||
| 07. In service date(s) | ||
| 08. Adopted by | US Navy | |
| 09. Production quantities | ||
| 10. Mechanism | Swinging breech block hinged on LHS with latch on top centre of breech, breech block swings to LHS. Spring loaded ejector rod below barrel. To cock action, striker is manually pulled to rear. Steel 7.75″ barrel, cast bronze frame and breech block | |
| 11. Weight | 4 3/4lb / 2.1kg | |
| 12. Mountings | ||
| 13. Practicality in action | ||
| 14. Comments / Other information | FOR PARACHUTE AND SIGNAL FLARES |