|Bofors 40 mm gun|
Something in the sky?
|Faction|| United States |
|Cost|| $10 |
|Factory||Artillery & Anti-air Base|
|“|| Anti-aircraft, always there to cover your butt.|
- American Bofors crew
|“|| Let's clean the skies for our boys!|
- British Bofors crew
The Swedish 40mm Bofors anti-aircraft gun was used by the allies in WWII. It was a towed anti-aircraft gun widely used by all belligerents during this war. Despite a limited range, it had good firepower thanks to its 40mm explosive shells. It is best used in large numbers, spread around the area to be defended and concealed to avoid early detection. With an average price, the Bofors is restricted to the defense of static positions like base camps, logistic lines or artillery parks as it is too slow and lacks armor necessary for the front line duty.
The Swedish Bofors 40mm AA gun was used heavily by Allied forces as a versatile and mobile weapon against aerial targets. The Bofors 40mm fires explosive shells towards aircraft, creating exploding flak which knocks out or disables airplanes. These AA pieces are weak on their own, however a group of these can wreak havoc on any aircraft squadron.
The Swedish Navy purchased a number of 2 pounder Pom-Poms from Vickers as anti-aircraft guns in 1922. The Navy approached Bofors about the development of a more capable replacement. Bofors signed a contract in late 1928. Bofors produced a gun that was a smaller version of a 57mm semi-automatic gun developed as an anti-torpedo boat weapon in the late 19th century by Finspång. Their first test gun was a re-barreled Nordenfelt version of the Finspong gun, to which was added a semi-automatic loading mechanism. Testing of this gun in 1929 demonstrated that a problem existed feeding the weapon in order to maintain a reasonable rate of fire. A mechanism that was strong enough to handle the stresses of moving the large round was too heavy to move quickly enough to fire rapidly. One attempt to solve this problem used zinc shell cases that burned up when fired. This proved to leave heavy zinc deposits in the barrel, and had to be abandoned. In the summer of 1930 they began experimenting with a new test gun that did away with controlled feed and instead flicked the spent casing out the rear whereafter a second mechanism reloaded the gun by "throwing" a fresh round from the magazine into the open breech. This seemed to be the solution they needed, improving firing rates to an acceptable level, and the work on a prototype commenced soon after.
During this period Krupp purchased a one-third share of Bofors. Krupp engineers started the process of updating the Bofors factories to use modern equipment and metallurgy, but the 40mm project was kept secret. The prototype was completed and fired in November 1931, and by the middle of the month it was firing strings of two and three rounds. Changes to the feed mechanism were all that remained, and by the end of the year it was operating at 130 rounds per minute. Continued development was needed to turn it into a weapon suitable for production, which was completed in October 1933. Since acceptance trials had been passed the year before, this became known as the 40 mm akan M/32. Most forces referred to it as the Bofors 40 mm L/60, although the barrel was actually 56.25 calibres in length, not the 60 calibres that the name implies.
The gun fired a 900g high explosive 40 × 311R (rimmed) shell at 850 m/s. The rate of fire was normally about 120 rounds per minute (2.0 rounds per second), which improved slightly when the barrels were closer to the horizontal as gravity assisted the feeding from the top-mounted magazine. In practice firing rates were closer to 80–100 rpm, as the rounds were fed into the breech from four round clips which had to be replaced by hand. The maximum attainable ceiling was 7,200m, but the practical maximum was about 3,800m. The gun was provided with an advanced sighting system. The trainer and layer were both provided with reflector sights for aiming, while a third crew-member standing behind them "adjusted" for lead using a simple mechanical computer. Power for the sights was supplied from a 6V battery.
The Swedish Navy decided it needed a smaller hand-swung weapon of 13 mm-25 mm size, and tested various designs from foreign suppliers. With the 40 mm well along in development, Bofors offered a 25 mm version in 1932, which was eventually selected as the 25 mm akan M/32. The first version of the 40 mm the Navy ordered was intended for use on submarines. The barrel was shorter at 42 calibers long, with the effect of reducing the muzzle velocity to about 700 m/s. When not in use, the gun was pointed directly up and retracted into a watertight cylinder The only known submarines that used this arrangement was the Sjölejonet class boats where the guns also served as deck guns, being powerful enough to be used against smaller vessels, the AA guns were later removed as the subs were modified with streamlined conning towers. The first order for the "real" L/60 was made by the Dutch Navy, who ordered five twin-gun mounts for the cruiser De Ruyter in August 1934. These guns were stabilized using the Hazemeyer mount, in which one set of layers aimed the gun, while a second manually stabilized the platform the gun sat on. All five mounts were operated by one fire control system.
Bofors also developed a towable carriage which they displayed in April 1935 at a show in Belgium, which allowed the gun to be fired from the carriage with no setup required, although with limited accuracy. If time was available for setup, the gunners used the tow-bar and muzzle lock as levers, raising the wheels off the ground and thereby lowering the gun onto supporting pads. Two additional legs folded out to the sides, and the platform was then leveled with hand cranks. The entire setup process could be completed in under a minute. Orders for the land based versions were immediate, starting with an order for eight weapons from Belgium in August 1935, and followed by a flood of orders from other forces including Poland, Norway, and Finland. It was accepted into the Swedish Army the next year, known as the 40 mm lvakan m/36, the lower-case m indicating an Army model as opposed to the capital M for Navy.
Strategies and TacticsEdit
- These anti-air guns should be concealed in forests in masses. It is a real nasty surprise for any passing aircraft overhead.
- When placing them in forests, add a few soldiers and/or a greyhound to defend them from incoming tanks and infantry.
Medium AA gun
- The British version fires faster that the USA version.
- The Bofors has 23 damage points against aircraft, versus the FlaK 20mm, where it has 18 damage points, although the Bofors fire slower.
- Bofors can also defeat MOST light infantry.
- It has a longer range than infantry weapons (excluding the Japanese sharpshooters) allowing them to act as an MG, providing support for your infantry.