- Yes
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75mm SP, Autocar
Design and Service History:
After the fall of France, the US Army immediately began to study the reasons behind the effectiveness of the German campaign against the French and British. One aspect highlighted was the advantages of highly mobile self-propelled artillery, which was something distinctively lacking from the US Army’s arsenal in 1941, meaning they were lacking in any vehicle capable of fulfilling this role. An idea was hatched to combine the already existing M1897A5 gun, which was suitable for mass production with the M3 half-track which was coming into production. After brief debate, this gun was placed on a chassis and designated the T12 GMC, and it was accepted into the Army on the 31st of October 1941.
An initial batch of 36 T12s were produced and used for testing, with another 50 build and transported to the Philippines. During testing these initial 36 T12’s were improved in numerous ways, including the inclusion of a Gun mount that raised the gun shield, and the replacement of said gun shield with the new M2A3 shield. The ability to mount a m2 Browning machine gun was also added, but this would later be removed. Happy with these changes the prototypes were sent to the Autocar Company for production under the new name of M3 gun motor carriage.
The British expressed an interest in this M3 GMC after seeing the Americans fielding it to some success in the North African Theatre, resulting in a small batch of 170 vehicles being supplied to Britain through the lend-lease program. These vehicles were assigned to British Armoured Car Regiments, which served as the reconnaissance component of their armoured formations under the name " 75mm SP, Autocar" . Two 75mm SP, Autocar would be assigned per squadron with a total of 8 in each regiment, where they would be used for Close Support, in order to smoke and suppress enemy positions, along with knocking out potential hard points and armour encountered on recce.
The 75mm SP, Autocar would first be used in the Tunisian Campaign with the Royal Dragoons, and would go on to serve in Sicily, Italy, and later in France, to much success due to their small profile and good off-road ability, in tandem with a punchy gun. They would be gradually retired from service when availability allowed them to be replaced with more modern armoured cars as the war went on, such as the Staghound MKII and the AEC MK III, though they would continue to see service in the front lines up until the cessation of hostilities. A respectable number of units are recorded as being present in western Europe in august of 1945, though their service would not continue long after the war, instead being replaced by the aforementioned armoured cars, when the shrinking of the Army post-war allowed for their disposal and replacement with more modern and capable vehicles.
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Vehicle Specification:
Mass 20,000 lb (9.1 t)
Length 20.46 ft (6.24 m)
Width 7.29 ft (2.22 m)
Height 8.17 ft (2.49 m) (including gun shield)
Crew 5 (commander, gunner, two loaders, and a driver)
Elevation 29° up, 10° down
Traverse 19° left, 21° right
Armor 0.25–0.625 in (6.4–15.9 mm)
Main armament 1 × 75 mm (3.0 in) M1897 gun (59 rounds)
Engine White 160AX, 386 in3 (6,330 cc), 6-cylinder, compression ratio: 6.44:1 147 hp (110 kW)
Power/weight 14.7 hp/ton
Transmission Constant-mesh
Suspension Semi-elliptical longitudinal leaf spring for wheels and vertical volute springs for tracks
Ground clearance 11.2 in (280 mm)
Fuel capacity 60 US gal (230 L)
Operational range 150 mi (240 km)
Maximum speed 47 mph (75 km/h)
Additional historical photos:
Sources:
- M3 Gun Motor Carriage - Wikipedia (Wiki page)
- Armoured car regiment - Wikipedia (Layout of armoured car regiments)
- M3 75mm Gun Motor Carriage (Additional history)
- M3 Gun Motor Carriage (75mm) Half-track Tank Destroyer (TD) (Specification)
- RCDs & M3 75mm GMC? - MLU FORUM (Forum post with listings of all British units equipt with the 75MM SP at the end of the war)