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Thread: New type of Brownings, November 1939

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    Default New type of Brownings, November 1939

    The 41 Squadron ORB records on 24 November 1939 that five airmen travelled from Catterick to the BSA Works at Birmingham to collect a new type of Browning machine guns for the Squadron’s Spitfires.

    Despite searching the 'net and the books I have on Spitfires, I cannot find any mention of a "new type" of Brownings from this period. Does anyone have any idea what change or technological advance may have occurred to the guns around this time?

    It does not appear to be a change to the aircraft (e.g. A/B variants) as they were flying Spit. Is and IAs, and did not change to B variants until they obtained the Mk. V in July 1941.

    Any ideas?

    Thanks
    Steve
    41 (F) Squadron RAF at War and Peace, April 1916-March 1946
    http://brew.clients.ch/41sqnraf.htm

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    Steve,
    You might find the following notes of interest; I have types these up over time for my own amusement. I am certain the answer is somewhere in here. Most readers might be surprised to see how many RAF aircraft in the 1937/38 (and probably later) were equipped with American-made (to RAF specifications!) Brownings.
    David D

    THE BROWNING 0.303” MACHINE GUN

    The Browning machine gun had been designed in the United States as along ago as 1900 in 0.300” calibre, although this was as an infantry weapon. However the RAF received an example of the latest version of this gun in July 1918, being one adapted in the USA as an air weapon and fitted with interrupter gear, and this was fitted to a Bristol Fighter for firing tests. However the end of the war saw any interest in this weapon evaporate, and the Air Ministry then became besotted with the idea of larger calibre weapons for air use, specifically those of 0.50” calibre.

    In 1923 a new version of the Browning 0.300 M/G was demonstrated to Air Ministry representatives at Enfield where the men from the Ministry were impressed by its performance. At this point Armstrong Whitworth acquired British manufacturing rights for the gun, and in April 1924 representatives from this firm visited the USA to obtain drawings and manufacturing data from Colt Firearms, as well as samples of both the 0.50 and 0.300 guns. Back in the UK, Armstrong Whitworth then adapted the smaller calibre weapon to operate with British 0.303” ammunition, and trials were held at Enfield. As a consequence of these trials, the Air Ministry placed an order with AW for six 0.303” guns in March 1926, which were to incorporate various modifications, particularly to do with the trigger motor for the guns. The first of these guns were delivered in March 1927 and was tested in 1927/28, while the RAE was busy designing a new trigger motor. The remaining five guns were not delivered until modifications to cure various defects noted in trials with the first gun were incorporated, and these duly appeared in the middle of 1929 after it was decided not to continue development of 0.50” guns after a long period of infatuation with this calibre. Incidentally another rush of blood to the head diverted Air Ministry attention in 1927 was to develop a light-weight machine gun (calibre 0.28”!) with a very high muzzle velocity, but this soon died a natural death the following year. However the new Browning gun still had major problems, and proper trials did not get underway until June 1931. The results of these trials, however, were impressive, the new weapons proving to be very reliable and easy to service.

    Meanwhile the Colt Patent Firearms company in the USA had been also improving their design and adapting it for aircraft duties by way of a complete redesign. An example of this new type (known as the 0.30 calibre M-2) was demonstrated to Air Ministry representatives at Crayford in January 1931, after which the Ministry (obviously greatly impressed) recommended that four such guns be ordered “and that all future trials should be done with that type”.
    These four weapons (two short barrel fixed “Pilot” type intended primarily for fighters, and two long barrel free “observer” type with muzzle attachment) were ordered through Vickers-Armstrongs (still acting as agents for Colt) and were duly delivered in mid-1932; both types featured belt feed. The Air Ministry observed that belt feed for an observer’s gun was a fundamentally flawed idea, but this gun had a firing rate 300 RPM greater than the pilot type, and moreover was more accurate due to its greater barrel and casing length. The decision was made to concentrate all energies on the observer gun, but adapt if for installation in fighter aircraft. Thus modified, this gun was tested in a Hawker Fury at the A&AEE during 1933 and early 1934, where problems with the synchronising gear trigger motor again caused a lot of grief, and a certain amount of trouble with fouling of the muzzle attachment was also experienced. However these trials, which also included the Darne and the Vickers central action machine guns, were completed in June 1934, and concluded that the Browning, although still requiring further development, was the best available as the standard gun for RAF fighters, and was thus recommended for production. Its rate of fire was improved over the old Mark V Vickers 0.303” gun (from 800 to 1,000 RPM), it was more reliable, was 5 pounds lighter, and enjoyed greater freedom from breakages in operation.

    The Air Ministry desired to purchase sufficient guns of the new type to equip two squadrons “for extended service trials”, but due to the long time lag expected before British made examples would be available, it was decided to order a further 60 guns directly from the Colt Patent Firearms Company in the USA in October 1934. As Vickers (which had merged with Armstrong Whitworth during 1927/28 to form Vickers Armstrongs, although the new conglomerate did not retain the manufacturing rights, but did remain as agents for the American company) were not interested in being a major producer of the Browning gun because of their interest in developing the VGO (Vickers Gas Operated) 0.303, it was decided that the Air Ministry itself should acquire manufacturing rights on behalf of the whole British Empire, and choose their own manufacturers. As it turned out, B.S.A. produced the vast majority of the Browning guns manufactured in the United Kingdom, but Vickers did in a fact also produce a small number. Based on their previous experience on modifying the original American design, as well as subsequent re-design, the Browning 0.303 was to become a rather different looking weapon. The initial modifications (1934) included introduction of a rear sear, which entailed a new lock frame and modifications to the bottom and side plates; Mod to feed lever to give equal length of feed to right and left-handed feed; mod to retaining pawl and filling pieces; re-design of cartridge stop to suit British ammunition; re-design of barrel casing to increase its rigidity; and chromium plating of muzzle end of barrel to reduce accumulation of fouling. The Colt-manufactured guns for the RAF incorporated all these mods except the first (because of its extensive nature). Before British production commenced, further mods were approved, including a new bottom plate (incorporating mounting for the loading mechanism, which had been a separate bracket on the earlier guns), new back block (made of forging instead of being built up, to strengthen gun), modification to external shape of barrel to assist production; and redesign muzzle attachment and flash eliminator, mainly to provide more efficient flash eliminator. Note that for wing mounted guns the loading mechanism was not used, the guns being loaded on the ground by armourers using a special loading lever.
    As is well known, many of the problems suffered by the earlier British-made Browning guns was a result of using cordite propellant in the cartridges; this generated higher pressures on firing, and also excessive amounts of fouling of the barrel, and was also very prone to “cooking off” rounds caused by the heat from the barrel after prolonged firing. The American armed forces used nitro-cellulose propellant which was considerably gentler in most respects than the rough and ready cordite.
    The RAF narratives do not state the total production of British-manufactured Browning guns from 1936 onwards, but they must have numbered in the hundreds of thousands, if not millions; it was noted that by mid-1941 British Browning production was running at 2,000 units per week (which equates to 104,000 per year), “at which figure it will be appreciated that quite small changes in design could effect considerable savings in man and machine hours”.

    (Extract from Chapter 2 “The Browning Gun’ from the volume in the RAF Narratives series dealing with armament, pages 27 - 29).

    The first British made Browning guns were delivered in March 1936, but it was not until the end of that year that any large quantities were being produced. To provide guns for new aircraft a further order for 600, and later for another 1,000 guns was placed with the Colt Company, so in all 1,660 American made Browning guns were purchased. By the time the gun was reaching the service in large quantities, all major defects had been eliminated by the various modifications that had been made (not described here). Trouble was experienced due to poor servicing, but this improved as the armourers gained experience with the new gun; in particular, ‘breeching up’ was liable to cause trouble. Unlike other guns previously used in the Service, it was possible with the Browning gun to adjust the fore and aft position of the barrel breech face relative to the breech block. If the barrel was too far back, the breech would not lock; whereas if it was too far forward, the cartridge case was not supported by the wall of the chamber and the pressure of the gases would cause the case to expand. This could cause the case to split and sometimes the neck of the cartridge case was left in the chamber causing a stoppage known as a ‘separated case’. The usual fault was to adjust the barrel too far forward and stoppages due to separated cases would occur.

    In Service use it was found that occasionally the firing pin would slip off the firing pin sear and give rise to stray shots when the guns were controlled by synchronising gear, and to prevent this the sear barrels were undercut. The introduction of this problem raised a question that became one of the main considerations when a modification was contemplated. Hitherto a modification had only affected the manufacture of the gun, but there were now so many guns in the Service that the question of the modification was to be carried out on the guns already issued, was more often more important than how it affected production. From then on, no modification could be made if it seriously affected interchangeability of existing weapons, or could not be applied to existing guns.

    During 1938, a series of endurance trials were carried out both on the ground and in the air, mainly for the purpose of assessing the maintenance requirements of new guns. The trigger motor was still not satisfactory; in particular the trip lever had a very short life; but as synchronising gear was obsolescent and would not be fitted to new fighters, it was decided not to re-design the unit. The air trials showed that the majority of stoppages were due to poor maintenance and as a result of these trials no further modifications to the guns were considered necessary.

    At that time Fighter Command stated a requirement for the Browning gun to be capable of firing bursts of 300 rounds duration. This was found to be impossible on existing guns as after firing 200 to 250 rounds continuously, so much fouling accumulated in the muzzle attachment that the barrel seized and stopped the gun. Even in normal use the muzzle attachment had to be cleaned at frequent intervals and the removal of the fouling from it was one of the most difficult maintenance operations on the gun.

    It was decided therefore, to re-design the muzzle attachment with a view to reducing the accumulation of fouling. After a number of experiments carried out at Messrs. B.S.A.’s works, a successful design was produced early in 1939, and samples were submitted to Fighter Command and the A&AEE for air trials. These trials were a complete success; not only did the new attachment permit bursts of 300 rounds to be fired, but it was possible to fire 6,000 rounds before it had to be cleared. This meant that even if 300 round bursts were not normally used, the maintenance of the gun would be greatly simplified, as the cleaning of the muzzle attachment would have to be carried out at less frequent intervals. The new attachment was approved for service use as a retrospective modification in May 1939. At this time B.S.A. were producing 500 guns a week and Vickers 100 per week; B.S.A. also planned a weekly production of 1,000 muzzle attachments by the following July. The guns made by Vickers were to be fitted with muzzle attachments made by B.S.A., thus leaving a weekly output of 400 attachments for retrospective modification of existing guns. It was estimated that between 15,000 and 20,000 guns would have been issued to the service by July; hence it would take approximately ten months before all guns in the Service were modified. This was the last major modification carried out on the Browning which became a thoroughly reliable service weapon.

    DEVELOPMENT 1939 – 1945.
    The gun at this stage was known as the Mk.II*, and the mark number was not altered again. From then on the Browning gun ceased to be a design problem and the majority of other minor alterations were to facilitate production. During the winter of 1939-40 aircraft were operating under more severe weather conditions than would be usual practice in peace-time and a considerable amount of trouble was experienced in certain aircraft due to guns failing to function at low temperatures. On most of the fighter aircraft, in particular the Spitfire and Hurricane, this had been foreseen and the gun compartments were lagged and heated from the engine exhaust. In other aircraft, particularly where guns were mounted in turrets, no provision for gun heating was made.

    From the design and development point of view, production was never a serious problem, in spite of the fact that the gun was not easy to make. It consisted of a large number of small and intricate components; the breech block in particular was a machinist’s nightmare. There were two reasons for the comparative absence of production problems. First, the entire production of guns was entrusted to two contractors: Messrs. B.S.A. and Messrs. Vickers Armstrong, who were both widely experienced in the manufacture of machine guns. The second reason was that the bulk of production was by Messrs. B.S.A., and from the time that it was decided to build Browning guns in this country, a very close liaison was maintained between B.S.A. and the technical staff of the Director of Armament Development (D.Arm.D.).

    Typed up 3/11/08.

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    Hi David

    Thanks for this excellent info and for taking the time to type it up and post it.

    Regards
    Steve
    41 (F) Squadron RAF at War and Peace, April 1916-March 1946
    http://brew.clients.ch/41sqnraf.htm

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