 = T30 Howitzer Motor Carriage = 
 
 The T30 Howitzer Motor Carriage ( HMC ) was a United States Army self @-@ propelled gun used in World War II . Its design was based on requirements for an assault gun issued by the Armored Force in 1941 and it was built as an interim solution until a fully tracked design was complete . 
 Produced by the White Motor Company , the vehicle was simply a 75 mm Pack Howitzer M1 mounted on a modified M3 Half @-@ track . It was first used in combat in the North African Campaign in November 1942 . It later served in Italy and France , and possibly in the Pacific . Some were later leased to French forces and the type was used as late as the First Indochina War in the 1950s . 
 
 = = Specifications = = 
 
 Based on the M3 Half @-@ track , the T30 's specifications were similar to its parent vehicle . It was 20 ft 7 in ( 6 @.@ 28 m ) long , 6 ft 5 in ( 1 @.@ 96 m ) wide , 8 ft 3 in ( 2 @.@ 51 m ) and high , and weighed 10 @.@ 3 short tons ( 9 @.@ 3 t ) . The suspension consisted of vertical volute springs for the tracks and leaf springs for the wheels , while the vehicle had a fuel capacity of 60 US gallons ( 230 l ) . It had a range of 150 mi ( 240 km ) and had a speed of 40 mph ( 64 km / h ) , and was powered by a White 160AX , 147 hp ( 110 kW ) , 386 in3 ( 6 @,@ 330 cc ) , six @-@ cylinder , gasoline engine , with a compression ratio of 6 @.@ 3 : 1 . It had a power @-@ to @-@ weight ratio of 15 @.@ 8 hp / ton . 
 
 = = = Gun specifications = = = 
 
 The T30 's main armament was a short barreled 3 @.@ 0 in ( 75 mm ) pack howitzer . The 75 mm Pack Howitzer M1 as mounted could depress nine degrees , elevate 50 degrees , and traverse 22 @.@ 5 degrees to each side . The vehicle had stowage for sixty rounds of 75 mm ammunition and , although it was not designed for anti @-@ tank use , it had a high explosive anti @-@ tank ( HEAT ) shell that could penetrate 3 in ( 76 mm ) of armor . The gun shield had 0 @.@ 375 in ( 9 @.@ 5 mm ) thick armor , designed to stop a .30 cal ( 7 @.@ 62 mm ) bullet from 250 yards ( 230 m ) away . 
 
 = = Development = = 
 
 The T30 HMC was originally conceived in 1941 as an interim design to fulfil the Armored Force 's requirement for an assault gun to equip tank and armored reconnaissance units . The Ordnance Department design was based on the M3 Half @-@ track in order that it could be brought into service quickly . A prototype vehicle was authorized in October 1941 armed with an M1A1 75 mm Pack Howitzer and a mount that was designed to fit on a simple box structure in the back of an M3 Half @-@ track . 
 Authorization for the production of two prototypes was given in January 1942 ; first deliveries of the vehicle were made the following month from the White Motor Company . As it was seen as a temporary solution it was never given type classification . In September 1942 , the T30 was partially replaced by the Howitzer Motor Carriage M8 ( the same gun on an M3 Stuart ) . After that , it was declared as " limited standard " . A total of 500 were produced , all by the White Motor Company . 
 
 = = Service history = = 
 
 The T30 HMC entered service in November 1942 , seeing action for the first time in the North African Campaign . In the 1st Armored Division , each armored regiment was issued twelve T30s . Of these , three were used in each battalion headquarters platoon and three were used in each regimental reconnaissance platoon . In addition , the 6th and 41st Armored Infantry Regiments were each issued with nine T30 HMCs , with three of them being allocated to the headquarters platoon in each armored infantry battalion . 
 Most infantry divisions in the North African Campaign deployed a " cannon company " equipped with six T30s and two 105 mm T19 HMCs . In one encounter in North Africa , the T30 was used in an attempt to destroy German tanks . Although the T30s fired several volleys , the German tanks were barely damaged and the T30s were ordered to retreat under the cover of smoke to prevent losses . After several similar experiences , U.S. forces ceased the practice of employing self @-@ propelled howitzers or mortars in direct combat with tanks . 
 The T30 also served during the Allied invasion of Sicily in 1943 , the war in Italy in 1944 , and possibly in the Pacific . It was removed from infantry division use in March 1943 , following changes in the organization of US infantry battalions , and was replaced by towed howitzers . The T30 was eventually replaced by the M8 HMC , which was based on the M5 Stuart light tank , and which began entering service around the same time as the T30 . Only 312 T30 HMCs were delivered in their original configuration , as the last 188 were converted back into M3 Half @-@ tracks before they were delivered . Later on , the U.S. leased several to French forces and some were used as late as the First Indochina War before the vehicle was retired from service in the 1950s . 
 
 