40mm L/56 Multipurpose Artillery |
|
Year of Construction: 1942 Bore: 40mm Weight of gun: 522kg / 1150lbs Weight of barrel: 91.6kg/ 202 lbs Length of gun: 3,779.5mm/ 148.8 ins. Length of bore: 2,250mm/ 88.853 ins. (56 calibers) Wt. of projectile: 0.9kg / 1.985 lbs Max. Range (Anti-Ship): 10.1km / 11,000 yds at 42° elevation Max. Effective Range: 2.7km /3,000 yds Ceiling (Anti-Air): 6.950 km/ 22,800 ft./ 7,600 yds at 90° elevation Max. Elevation: 90° Rate of Fire: 120 - 160 rounds/min/barrel; governed by the speed of loading 4 round clips. Crew: Twin - 7; Pointer, Trainer, Gun Captain, 4 Loaders (2/Barrel)
As commissioned in 1944, the Slater carried one twin 40 mm Gun with Mk 51 Director, located on the Superstructure (01 level) in the "X" position. A set of torpedo tubes (3) were located on this deck just aft of the stack.
Shortly after her shakedown cruise in June 1944 it was decided to remove the torpedo tubes and augment the antiaircraft battery by placing four more single army type 40 mm gun mounts at this location. It is assumed these were used due to availability problems for the twin 40s. Pictures of the Slater's tour as a target ship and convoy pictures show these four single mounts. In June 1945 prior to its Pacific tour these four single mounts were replaced by two twin mounts with MK51 gun directors with lead computing sights located in tubs adjacent to the guns. These continual upgrades are a good example of how the Navy continually improved and up-gunned its ships to meet changing threats. |
FIRE ! ...
CEASE FIRE !
|
|
The 40mm L/56, a product of the Swedish Bofors company, probably ranks as the most efficient close-in air defence weapon on any warship during WWII. A single--barrelled air-cooled version was first examined by the U.S. Army in 1937. In 1940 the Chrysler Corporation, one of America's "big three" auto manufacturers, agreed to build them using British drawings. A vast improvement over the Navy's existing 1.1-inch (27.94mm) AA weapon, the USN acquired some of these, mounting them in submarines, destroyers, and some lighter vessels (the USS Slater had four of these for a period after removal of her torpedo tubes). Later in 1940, a twin-barrelled example arrived from Sweden via Finland and, using British and Dutch plans, the York Lock & Safe Co. undertook to manufacture them for the Navy, though it did not receive formal licence from Sweden to do so until June of 1941. The first twin Bofors was produced in January of 1942. A quadruple version followed in April. Bofors guns soon began appearing fleet-wide, though not until mid-1944 was demand satisfied (and not for the Slater until May of 45). The 40mm L/56 came in two basic mountings, the smaller being a twin-barrelled version used mostly in destroyers and lighter craft. The large quadruple mount, basically two twins side-by-side, due to its weight was found primarily in carriers, battleships, and cruisers, though a few DEs in the pacific Theatre had its "X" position gun upgraded to a quad mount. The efficient 40mm proved adequate for all close-in air defence duties until the kamikaze attacks of the last nine months of the war. Each of the twin 40mm's fired 160 rounds-per-minute, per barrel with an approximate effective range of 4000 yards. The guns were manned by seven men with ammunition passers added to the crew as required. The crew consisted of a gun captain, pointer, trainer, two first loaders and two second loaders. Ready service ammunition was held in racks welded to the "gun tub", a steel bulwark built around the gun to protect the crew. When ammunition in the ready service racks was used up, they would be refilled from below. Despite all this, it was not devastating enough to stop many diving suicide planes from crashing into their targets. Part of the problem was that the 40mm couldn't handle the VT proximity fuse, the 76mm guns being the smallest weapons able to handle that devastating item. Evenstill, the Bofors 40mm remained the primary close-in anti-aircraft weapon of smaller vessels until the Japanese surrender. |
 Top-Rear View of 40mm Starboard Side, Superstructure Deck
|
 |  |
| 20 MM | 3 IN/50 Cal | 40 MM | K-Gun | Hedgehog | DC Racks | DC Patterns | Torpedos (tbp) |
| Back to Weapons Index | Back to Superstructure |
24 January 2000 (mjs)
URL:http://www.dmna.state.ny.us/slater/weapons/40mm.html