| Canon de 340 mm Modèle 1887 | |
| Origin: | France |
| Type: | Naval gun |
| Is Ranged: | YES |
| Is Artillery: | YES |
| Used By: | France |
| Wars: | First World War |
| Part Length: | 14.133m (46.368feet) (42 caliber) |
| Cartridge: | Separate-loading, bagged charge |
| Cartridge Weight: | (APC shell) |
| Rate: | 1 round per four minutes |
| Elevation: | −4° to +10° |
| Filling Weight: | 7.7kg-30kgkg (17lb-70lbkg) |
The Canon de 340 mm Modèle 1887 was a heavy naval gun used as the main armament of several ships of the French: Marine Nationale (French Navy) before World War I. It equipped the and the coast-defense ships and .