#1010
Post
by Richard Anderson » 08 May 2022, 20:08
The subject of the Browning 37mm guns is pretty complex. In December 1920, John Browning offered to design a 37mm automatic aircraft gun to fulfill the requirements of the Chief of Ordnance, Major General Clarence C. Williams, for any fee designated by the government. Williams immediately accepted the generous offer and Browning began work in January 1921. In just two months Browning designed an enlarged version of the .50 caliber machine gun and built an initial pilot that fired the antiquated Hotchkiss 37mm round. The gun was tested first near Browning’s Ogden, Utah home and then later in the same year at Aberdeen Proving Ground. While Ordnance was enthusiastic, they also now wanted an aircraft gun with a muzzle velocity of 2,000 F.P.S., much greater than the 1,400 F.P.S. capability of the Hotchkiss-based guns, as well as an antiaircraft gun with a muzzle velocity of 2,000 to 3,000 F.P.S. Browning designed a more powerful 37 x 120R cartridge and a second gun in an attempt to meet the new requirement. However, tests at Aberdeen from January to May 1924 with gradually more powerful cartridge loads did not exceed 1,350 F.P.S. muzzle velocity. Undeterred, Browning completed a third gun in early 1925 with a new 37 x 123B cartridge and demonstrated it and the earlier gun at Aberdeen in June. It achieved the 2,000 F.P.S. muzzle velocity goal set by Ordnance and outperformed its only competition, an Ordnance design.
Considerable confusion exists identifying these three Browning guns, some sources identify both the first two as the M1924, but they were different guns. The third gun, also known as the M1925, initially used the same 37 x 123B cartridge as the M1924, but then was modified and rebuilt in 1926 to fire a much larger 37 x 224R cartridge in order to reach the 3,000 F.P.S. goal. Even more confusingly, in fiscal year 1926 (i.e. after 30 June 1926) Ordnance instituted the 'T' number system for Test items and various earlier test items considered legitimate "pilot" models were given numbers retroactively. However, Ordnance did not assign them systematically – or chronologically – and so the last built of the three Browning guns, the 3,000 F.P.S. M1925 became the T2, the second 1,350 F.P.S. M1924 gun became the T3, while the first prototype M1921 gun apparently never received a T number.
Despite the typical Browning qualities of simplicity and reliability, he developed the guns in a period of growing fiscal austerity, which restricted further work on them. Browning’s death in November 1926 also left a considerable void. Testing of the guns continued in 1926 and 1927. The tests demonstrated the high muzzle velocity of the T2 caused excessive wear at the muzzle, while Ordnance considered the long, thin barrel too weak. Stoppages from failure to eject spent cases were also a frequent problem. The Colt Firearms Company continued work on solving the problems of the T2 after Browning’s death and Ordnance authorized manufacturer of a second pilot, designated T2E1, with a heavier muzzle and water-jacket for cooling. It utilized a slightly modified 37 x 223R cartridge, which became standard. Finally, in May 1927 Ordnance accepted the T2E1 as the 37mm Antiaircraft Gun M1927, then changed it almost immediately to the M1, but none were authorized for production except for two production pilots. In December 1928, the Chief of Coast Artillery, Major General Andrew Hero plaintively reported the 37mm Antiaircraft Gun M1 was still “in the hope stage”. Tests of various carriages continued into the 1930s, using the same three completed M1 guns. In 1937, the existing guns were modified to fire at a lower muzzle velocity of 2,800 F.P.S. in order to improve accuracy and decrease barrel erosion. The modified guns were designated M1E1 and after the water jacket was removed as well they were standardized in October 1938 as the M1A1. Unfortunately the guns were still inaccurate, so the rifling was changed and the muzzle velocity decreased again to 2,600 F.P.S., resulting in the M1A2. In February 1939, nearly fourteen years after the first demonstration of the T2 by Browning at Aberdeen, General Marshall testified there was only a single complete gun M1A2 Gun and Carriage ready. By 1 May 1940 there were still only 15 of a planned 1,423 guns on hand with the Coast Artillery Corps.
Similar desultory work continued on the 37mm T2 by the Air Corps, which began renewed development of a 37mm aircraft cannon in 1935. In December 1939, the final development type, the T9, was standardized as the 37mm Aircraft Cannon M4. However, despite all the effort expended on antiaircraft and aircraft cannon, Ordnance never developed a purpose-designed tank gun from Browning’s work, although the M1924 (T3) was used as an ad hoc tank gun in the Cunningham light tank series. Finally, in 1934-1935 Ordnance tested the T2 as a tank gun with cartridges loaded to both 2,000 and 3,000 F.P.S., but it was not accepted.
As best I have been able to tell from the available records, Light Tank T1 and T1E1 armament was a M1916 37mm Gun. Light Tank T1E2 and T1E3 armament was the Browning-designed hi-velocity 37mm M1924 gun. The Light Tank T1E4 used the low-velocity Browning M1924 T3.
Richard C. Anderson Jr.
American Thunder: U.S. Army Tank Design, Development, and Doctrine in World War II
Cracking Hitler's Atlantic Wall
Hitler's Last Gamble
Artillery Hell