6-inch/30-caliber gun

The 6"/30 caliber gun Mark 1 (spoken "six-inch-thirty-caliber") were used for the primary battery of the United States Navy's dispatch vessel with the Mark 2 being used in the secondary batteries for its "New Navy" protected cruisers , , and and the Mark 3 used for the primary and secondary batteries in the succeeding early protected cruisers in addition to secondary batteries in the "Second Class Battleships" and .

Design The 6-inch/30 caliber Mark 1, 2, and 3 guns were developed before the Spanish–American War and still used black powder or brown powder, in later years they were not considered strong enough to withstand the higher chamber pressures generated by the newer smokeless powder adopted around 1898 and were obsolete before the start of World War I.

The Mark 1, gun No. 1, was constructed of tube, jacket, 16 hoops, an elevating band, and integral trunnions with a screwed-on muzzle bell. The Mark 2 also trunnioned with the Mark 2 Mod 1, which had only 10 hoops, a jacket, and a chamber liner; the Mod 2 was the same, but with a full-length liner. All Mark 1 and Mark 2 guns were constructed to a length of 30 calibers. In 1895, all Mark 2s were ordered to be converted to rapid-fire, fixed ammunition. This was done in 1898–1902 with gun No. 2 being delivered in November 1898 for use in Atlanta.

The Mark 3 was trunnioned as the Mark 1 and Mark 2, but was built in three different caliber lengths, 30, 35, and 40, in eight different Mods, Mod 0 – Mod 6, and Mods 8 and 9. Mod 0 was 30-caliber, with Mod 1 being 35-caliber. All 30- and 35-caliber Mods had a liner, 10 hoops, and a jacket. Mod 2 was a 40 caliber with only eight hoops. Mod 3 was again 30 caliber but introduced the use of case (semi-fixed) ammunition. The Mod 4 was experimental in that it eliminated the trunnions and used a threaded sleeve. Mod 5s were reworked, enabling Mod 1s to handle case ammunition. As with the Mod 5, the Mod 6 was a Mod 2 reworked to handle case ammunition. The Mod 7 was skipped, and no drawings exist for this Mod. The Mod 8 was another Mod 2 rework, this time removing the trunnions and replacing them with a threaded sleeve. The last Mod was Mod 9, using a Mod 3 gun and a full-length liner.

Naval Service ShipGun InstalledGun MountMark 1: 6"/30 caliberMark 1: 1 × shifting pivotMark 2: 6"/30 caliberMark 2: 6 × muzzle pivot mountMark 2: 6"/30 caliberMark 2: 6 × muzzle pivot mountMark 2: 6"/30 caliberMark 2: 8 × muzzle pivot mountMark 3: 6"/30 caliberMark 3: 6 × central-pivot Mark 3: 4 × 6"/30 caliber Mark 3: 2 × 6"/35 caliberMark 4: 6 × central-pivot w/single-piece slide Mark 3: 6"/30 caliber (as built) Mark 3: 6"/40 caliber (refit 1901–1902)Mark 3: 12 × central-pivotMark 3: 6"/30 caliberMark 3: 6 × central-pivotMark 3: 6"/30 caliberMark 3: 6 × central-pivotMark 3: 6"/30 caliberMark 3: 12 × central-pivotMark 3: 6"/40 caliberMark 3: 2 × central-pivotMark 3: 6"/40 caliberMark 3: 2 × central-pivotMark 3: 6"/30 caliberMark 4: 6 × central-pivot w/single-piece slideMark 3: 6"/30 caliberMark 4: 6 × central-pivot w/single-piece slideMark 3: 6"/30 caliberMark 4: 6 × central-pivot w/single-piece slideMark 3: 6"/30 caliberMark 4: 6 × central-pivot w/single-piece slide

Preserved weapons At least five guns of this type are preserved: One gun from Maine (ACR-1) in Washington, DC at the National Museum of the United States Navy. One gun from Maine (ACR-1) in Portland, Maine at Fort Allen Park. One gun from Maine (ACR-1) at the city hall in Alpena, Michigan. Two guns from Concord (PG-3) at the Veterans Memorial Museum, Chehalis, Washington.

See also Weapons of comparable role, performance, and era BL 6 inch gun Mk II – VI approximate British equivalent

Notes

References

6-inch/30-caliber gun

Bron en licentie