3" 50 GUN

The 3"50 gun could fire at the rate of 40 rounds per minute per barrel or 80 rounds per minute for the entire mount. An SPG-34 radar atop the gun measured target range which was used to calculate the "lead-off" angle of the gun. When shooting at aircraft, the gun has to fire at the place in the sky where the aircraft will be when it meets up with the round which has just been fired. The 3"50 magazine had a capacity of 1,518 rounds.  (Photo by Jerry Proc) 
Prior to HAIDA'S first tour of duty in Korea, a 3" 50 gun was installed during the the conversion refit and occupies the space formerly held by the Twin Four mount or the 'X' mount of World War 2. These guns fired a round which was 3 inches in diameter. The length of the gun barrel was 150 inches, or 50 times the diameter of the round, hence the name 3" 50 calibre. This gun was designed by the US Navy primarily as an anti- aircraft gun but it could be used in a general purpose application as well. Unlike the twin, four inch guns, these guns could only be operated electrically and without manual backup.
The four "Lazy Susan" projectile carriers had to be be continuously supplied from the ready-use compartment just forward of the gun. It took a crew of 15 to operate this gun and keep it supplied with ammunition. Different colours on the projectile tips indicated different fuze types. Empty shell casings would be kicked over to each side of the gun where they fell into a wire cage. (Photo by Jerry Proc) 
During both tours of duty in Korea , the 3"50 gun was used to fire at trains which operated on the coastal railway. The US Navy, in an effort to boost morale, issued a challenge to all ships by forming an elite group called the "Trainbusters Club". Membership in the club was open to all ships. HAIDA joined in December 1952 when she scored a direct hit on the engine of a train. HAIDA'S crew proved adept at this new sport thus earning one of the top spots in the "club."


The 3 in 50 gun aboard HAIDA is a Mark 8 Mod 2 fitted on a MK XXI Mod 1 power mount.

Maximum barrel elevation and depression:  +85 to -15 degrees
Training and laying speed: Training 30 deg/sec; laying 24 deg/sec
Rate of fire: 40 rounds per minute per barrel or  80 rounds per mount. The rate of fire was controlled by the drive motor gearing which could be changed.
Total weight of round: 24 lbs.
Weight of shell only: 13 lbs.
Maximum horizontal range at 45 degrees elevation - 14,600 yards
Maximum vertical ceiling - 29,800 feet (9,933 yards)
Fuse type: VT (proximity)  and DA
Other round types: Star shell, practice round (no charge in the shell) and a bore clearing charge for the gun.
Misc: 10,000 yards was the engagement range. Accuracy also improved  if the target was closer.


Pictured here is HAIDA'S 3"50 gun crew and was likely taken during one of HAIDA'S tours of duty in Korea. (HMCS HAIDA Archives photo
Above and below: Within feet of the 3in 50 gun, this ready-use locker could accommodate 200 rounds of ammunition. This space was also used as a shelter by the gun crew. Interlocking cannisters prevented the rounds from moving around while the ship was at sea. (Photos by Jerry Proc)


1) http://www.dlsu.edu.ph/offices/osa/rotc/pdf/ms2/naval-ordinance-gunnery-b.pdf
2) Battle Ensign Flying by Barry Gough.


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Jul 5/13