US Navy 20-Pounder (4-Inch) Dahlgren Rifle at NSWC Dahlgren Division - Photo by Haze Grey History.
A US Navy 20-Pounder (4-Inch) Dahlgren Rifle is displayed at NSWC Dahlgren Division. These photos were taken by Haze Grey History in 2023. Many thanks for the permission to use them here.
The 20-Pounder was a bronze rifle first manufactured in 1863. One hundred were manufactured from 1863 to 1867. In size and weight (about 1,350 pounds) it is very similar to the smoothbore 24-Pounder boat howitzer.
Originally, all of these 20-Pounder Dahlgren Rifles were muzzle loaders. Beginning in 1876 the Navy began converting a number - eventually thirty-six - to breech loaders. This is one of the conversions. The lugs for a firing hammer were removed in the conversion process - suggesting that the converted gun was fired using a friction primer.
This Dahlgren was originally cast at the Washington Navy Yard in 1864 as 20-Pounder Rifle Number 41. It first served aboard the Sassacus-class gunboat USS Pontoosuc. Pontoosuc participated in both attacks on Fort Fisher. Her captain’s report for specifically mentions firing five rounds from the “20-Pounder Rifled Howitzer” at the fort on January 13th, 1865. I suspect, though, that Pontoosuc’s armament included a 24-Pounder smoothbore and 20-Pounder rifle on each side of the ship. Photographs of sister ships in 1864-1865 appear to show such howitzers mounted on the paddle boxes.
Post-war, Number 41 served aboard USS Ticonderoga from 1871 to 1874. In 1883 this 20-Pounder was converted into a breechloader which received the new registry number 33. The 20-Pounder BL Number 33 next served aboard USS Shenandoah from 1883 to 1886. It served aboard USS Marion from 1891 to 1894. Its final service was aboard the old razee frigate USS Independence from 1895 to 1897.
This 20-Pounder is missing its breech block.
An unmodified (muzzle loading) 20-Pounder Dahlgren Rifle photographed at the Washington Navy Yard in 2024. Note the lug for the firing hammer and the elevating screw.
