| 10"/40 caliber Mark 3 Naval Gun | |
|---|---|
 USS Washington (ACR-11) - 10-inch gun practice. | |
| Type | Naval gun |
| Place of origin | United States |
| Service history | |
| In service | 1902 |
| Used by |  United States Navy |
| Wars | World War I |
| Production history | |
| Designer | Bureau of Ordnance |
| Designed | 1899 |
| Manufacturer | U.S. Naval Gun Factory |
| No. built | 21 (Nos. 27–47) |
| Variants | Mark 3 |
| Specifications | |
| Mass |
|
| Length | 413 in (10,500 mm) |
| Barrel length | 400 in (10,000 mm) bore (40 calibers) |
| Shell | 510 lb (230 kg) armor-piercing |
| Caliber | 10 in (254 mm) |
| Elevation | -3° to +14° |
| Traverse | −150° to +150° |
| Rate of fire | 2 – 3 rounds per minute |
| Muzzle velocity | 2,700 ft/s (820 m/s) |
| Effective firing range | 20,000 yd (18,288 m) at 14.5° elevation |
The 10"/40 caliber gun Mark 3 (spoken "ten-inch-forty-caliber") was used for the main batteries of the United States Navy's last generation of armored cruisers, the Tennessee-class. The Mark 3s were the last, and most powerful, 10-inch (254 mm) guns built for the US Navy.[1]