| Cannone da 203/53 Ansaldo | |
|---|---|
 Forward guns on Fiume, 1935 | |
| Type | Naval gun |
| Place of origin | Italy |
| Service history | |
| In service | 1931–1944[1] |
| Used by | Regia Marina |
| Wars | Second World War |
| Production history | |
| Manufacturer | Gio. Ansaldo & C. |
| Specifications | |
| Mass | 19.5 tonnes[2] |
| Barrel length | 424 inches (10.8 meters)[2] |
| Shell | 125 kilograms (276 lb)[2] |
| Caliber | 8-inch (203 mm)[2] |
| Muzzle velocity | 900 meters per second (2953 ft/sec)[2] |
| Maximum firing range | 31,324 metres (34,256 yd)[2] |
The 203 mm/53 Ansaldo was the main battery gun of Italy's most modern Washington Naval Treaty heavy cruisers. This treaty allowed ships of not more than 10,000 tons standard displacement, and with guns no larger than 8 inches (203 mm), to be excluded from total tonnage limitations on a nation's capital ships.