Item Description
Original Items: Only One Lot Available. This is a fantastic opportunity to add some rather rare gun components to your collections, perfect for a US Navy or Ordnance display! The components may or may not have come from the same weapon system but they still make for fantastic mementos from the past!
The Bofors 40 mm Automatic Gun L/60 is an anti-aircraft autocannon, designed in the 1930s by the Swedish arms manufacturer AB Bofors. The gun was designed as an intermediate anti-aircraft gun, filling the gap between fast firing close-range small caliber anti-aircraft guns and slower firing long-range high caliber anti-aircraft guns, a role which previously was filled by older outdated guns. The Bofors 40 mm L/60 was for its time perfectly suited for this role and outperformed competing designs in the years leading up to World War II in both effectiveness and reliability.
The Parts In This Lot:
- Pointer’s Handwheel: This is an adjustment wheel used for “Gun Laying” which is the process of aiming the weapon system. Gun laying is a set of actions to align the axis of a gun barrel so that it points in the required direction. This alignment is in the horizontal and vertical planes. A gun is "traversed" (rotated in a horizontal plane) to align it with the target, and "elevated" (moved in the vertical plane) to range it to the target. Gun laying may be for direct fire, where the layer sees the target, or indirect fire, where the target may not be visible from the gun. Gun laying has sometimes been called "training the gun".
The need to engage balloons and airships, from both the ground and ships, was recognised at the beginning of the 20th century. Aircraft were soon added to the list and the others fell from significance. Anti-aircraft was direct fire, the layer aiming at the aircraft. However, the target is moving in three dimensions and this makes it a difficult target. The basic issue is that either the layer aims at the target and some mechanism aligns the gun at the future (time of flight) position of the target or the layer aims at the future position of the aircraft. In either case the problem is determining the target's height, speed and direction and being able to 'aim-off' (sometimes called deflection laying) for the anti-aircraft projectile time of flight.
- Front “Spider” Sight: The sights used on anti aircraft guns used a sight that was designed to help the gunner compensate for altitude, range and airspeed of the target aircraft. They were used much like the modern mil-dot reticle with each intersecting line and opening representing a known value of size, speed and distance and its relation to the gun's capabilities. With the introduction of the proximity fuze, Navy gun crews were able to inflict heavy damage on attacking waves of Japanese planes.
- Rear “Peep” Sight Aperture: The peep sight is a combination of a bead or post front sight and a round hole set on the rifle's receiver close to the shooter's eye, though this one is the standard “plus sign” with a central hole. To aim, you center the target in the rear peep or aperture sight, and then bring the front sight into the center of the hole.
- Data Plate:
40mm Machine Gun Mech
MARK 1 MOD 1
INSPECTOR NCC SERIAL NO. 27461
Chrysler Corporation
Detroit, Mich.
WEIGHT 778 LBS 1943
In order to supply both the U.S. Army and U.S. Navy with much greater numbers of the guns, Chrysler built 60,000 of the guns and 120,000 barrels through the war, at half the original projected cost, and filling the Army's needs by 1943. Over the lifetime of the production, their engineers introduced numerous changes to improve mass production, eventually halving the overall time needed to build a gun. Most of the changes were in production methods rather than the design of the gun itself: for example, milling from steel block was replaced by stampings and castings whenever possible, and Amplex division of Chrysler (which normally manufactured oilite) produced nine parts by sintering. York Safe & Lock also produced the weapons, though its attempts to coordinate drawings across the program were unsuccessful, and this responsibility was transferred to the Naval Gun Factory in July 1943.
There were many difficulties in producing the guns within the United States, beyond their complexity (2,000 subcontractors in 330 cities and 12 Chrysler factories were used to make and assemble the parts). The drawings were metric, in Swedish, with loose tolerances for hand fitting and read from the first angle of projection. Chrysler had to translate to imperial measures and English language, fix absolute dimensions, and mirror/reorder the drawings to the third angle of projection. Chrysler engineers also tried to simplify the gun, unsuccessfully, and to take high-speed movies to find possible improvements, but this was not possible until near the end of the war.
Swedish blueprints had many notes on them such as "file to fit at assembly" and "drill to fit at assembly," all of which took much production time in order to implement. Thirdly, the Swedish mountings were manually worked, while the USN required power-worked mountings in order to attain the fast elevation and training speeds necessary to engage modern aircraft. Fourthly, the Swedish guns were air-cooled, limiting their ability to fire long bursts, a necessity for most naval AA engagements. Finally, the USN rejected the Swedish ammunition design, as it was not boresafe, the fuze was found to be too sensitive for normal shipboard use and its overall design was determined to be unsuitable for mass production.
A lovely grouping ready for further research and display!
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