| EOC 12-inch L/23.5 | |
|---|---|
 As depicted in March 1877 | |
| Type | Naval artillery |
| Place of origin | United Kingdom |
| Service history | |
| Used by | None (prototype) |
| Production history | |
| Designer | Elswick Ordnance Company |
| Manufacturer | Elswick Ordnance Company |
| Produced | 1877 |
| No. built | 1 |
| Specifications | |
| Mass | 39 long tons (40 t) |
| Length | 282 inches (7.16 m) L/23.5 |
| Caliber | 12 inches (30.5 cm) |
| Muzzle velocity | 1,650 feet per second (500 m/s) |
The EOC 12-inch L/23.5 or '39-ton breechloading gun', was an experimental breechloading gun designed and manufactured by the Elswick Ordnance Company also known as Armstrong. The gun was made to profit from recent discoveries about how gunpowder behaved. These required longer guns and made muzzleloading troublesome. The gun seems to have been a failure.