The 5-Inch 40 Caliber Mark 2 Gun of USS Olympia
5"/40 Mark II Number 79 aboard Olympia in the forward position on the port side battery (August 2024 photo)
5-Inch BLR Mark II Number 79 was manufactured at the Washington Navy Yard in 1904. As the single 5-Inch 40 Caliber gun now aboard the Protected Cruiser Olympia, it represents the gun deck battery of ten 5"/40s that USS Olympia carried at the time of the Battle of Manilla Bay. As a museum ship, the balance of 5-Inch guns now aboard are the later 5"/51 representing her WWI armament. Even though No. 79 is the correct type for 1898, it is mounted on a later type of pedestal mounting which was manufactured in 1916. The 1899 photos give a glimpse of the "Rapid Fire Recoil Mount" on which Olympia's 5"/40s were originally mounted.
A weight of 7208 pounds is stamped on the breech of Number 79. Note that this weight is only the tube. The weight of slide in which No. 79 is mounted weighs 2561 pounds. The pedestal (or 5" Stand Mark III Mod 1 Number 39) weighs 2080 pounds. I couldn't tell if the breech block was marked with its own weight. Assuming I've not missed a major component, this seems to indicate a total weight of around 12,000 pounds.
As the focus of my page is usually the mid-19th Century, its interesting to compare this total weight with the standard broadside cannons of the Civil War navy: a 9-Inch Dahlgren (about 9,200 pounds) or a 6.4-Inch Parrott (about 9,800 pounds) for the tube. Carriage weight varies, but a post-war iron broadside carriage weighed about 1,200 pounds. While the 5"/40 has the lowest shell weight of the three types at 50 pounds verses 70-ish pounds for the two Civil War era cannons, velocity and rate of fire more than make up the difference with the mid century types. As silly as this comparison is, remember that 9-Inch Dahlgrens and Parrott Rifles were still at sea on the US Navy's oldest cruising warships when Olympia commissioned. USS Kearsarge, which was wrecked while on active duty in 1894, still carried both Dahlgrens and Parrotts.
5"/40 Mark II in the same position (port forward) in 1899. Naval History and Heritage Command Photo 43337
5"/40 Mark II Number 79 aboard Olympia in the forward position on the port side battery (August 2024 photo)
5"/40 aboard USS Olympia in 1899. Note how far the training and elevating wheels extend beyond the breech on the original mountings. Also note the adjustable "iron sight" little different from that which was used on mid-century Dahlgrens. Naval History and Heritage Command Photo: 43368
The Breech of Number 79 on top of the tube.
Breech block of Number 79 - which is also numbered 79
Admiral's Cabin aboard USS Olympia - note the 5"/40 Mount - again with the elevating/training wheels extending past the breech. Naval History and Heritage Command Photo 43330
Training gear and telescopic sight on the 1916 mount
Two of the 5"/40s can be seen in this 1899 photo of Olympia's gun deck. Naval History and Heritage Command Photo 44336
Elevating Gear and Sights on the left side of Number 79
5" Stand Mark III Mod 1 Number 39
5" Slide Number 39
Training Gear of Number 79
5" Sight Mark XII Mark ?
Sights on the Left side of Number 79
I visited Olympia in August of 2024 and was very impressed with the ship and the way in which she is interpreted.
Most of the 5-Inch guns aboard Olympia now are 5"/51s which represent her WWI armament
Cutaway Drawing of the 5" RF Recoil Mount in Ingersoll, Royal Rodney. "Text Book of Ordnance and Gunnery Compiled Compiled and Arranged for Naval Cadets, U.S. Naval Academy." Deutch Lithographing and Publishing Company. Baltimore, 1894.
