M3 howitzer

105 mm Howitzer M3
A M3 howitzer outside the Army Museum in Honolulu, Hawaii.
Type	Light Howitzer
Place of origin	United States
Service history
In service	1943–Present
Used by	United States
Wars	Second World War
Production history
Designed	1941
Produced	1943-45
Number built	2,580
Specifications
Weight	2,495 lb (1,130 kg)
Length	12 ft 11 in (3.94 m)
Barrel length	Bore: 5 ft 6 in (1.68 m) L/16 Overall: 6 ft 2 in (1.88 m) L/17.9
Width	5 ft 7 in (1.70 m)
Height	4 ft 2 in (1.27 m)
Shell	105x372R
Caliber	105 mm
Breech	Horizontal block
Recoil	Hydropneumatic, constant
Carriage	split trail
Elevation	-9° to 30°
Traverse	45°
Rate of fire	Burst: 4 rpm Sustained: 2 rpm
Muzzle velocity	1,020 ft/s (311 m/s)
Maximum firing range	HE: 8,300 yd (7,600 m)

The 105 mm Howitzer M3 was a U.S. light howitzer designed for use by airborne troops. The gun utilized the barrel of the 105 mm Howitzer M2, shortened and fitted to a slightly modified split trail carriage of the 75 mm pack howitzer.

The howitzer was used by the U.S. Army during World War II. It was issued to airborne units and the cannon companies of infantry regiments.

Development and production

The process of building airborne forces in 1941 led to a requirement for an air portable 105 mm howitzer. The weapon, initially designated T7, featured a barrel from the 105mm Howitzer M2, shortened by 27 inches (690 mm) and combined with a recoil system and carriage of the 75 mm field howitzer. A prototype reached trials at Aberdeen Proving Ground in March 1942.

The howitzer was designed to fire the same ammunition as the longer M2. However, it turned out that shorter barrel resulted in incomplete burning of the propelling charge. The problem could be solved by use of faster burning powder. Otherwise the design was considered acceptable and was standardized as 105 mm Howitzer M3 on Carriage M3. The carriage was soon succeeded by the M3A1, which had trails made from thicker plate. Even stronger tubular trails were designed, but never reached production.

The production started in February 1943 and continued until May 1944; an additional bunch was produced in April–June 1945.

Production of М3, pcs.
Year	1943	1944	1945	Total
Produced, pcs.	1,965	410	205	2,580

Service

Even though the M3 was not mentioned in the February 1944 Tables of Organization and Equipment (TO&E), shortly before the Normandy Airdrops some airborne divisions received a 105 mm glider field artillery battalion equipped with them as a supplement to their existing three 75 mm howitzer battalions (designated the M1A1 during World War II). 1/4 ton jeeps were used as prime movers. Later increased to four battalions, one, between 1943 and 1945, was converted to 105mm M3. The weapon was finally authorized as an option by the December 1944 TO&E and, by 1945, employed by all airborne divisions in the European Theater.

The M3 was also issued to the cannon companies of infantry regiments (six, in three platoons of two). Often the cannon companies were integrated into the division artillery. Infantry typically used 1½ ton trucks as the prime mover.

A small number of M3s were supplied via lend lease channels to France (94), United Kingdom (2) and countries of Latin America (18).

Variants

M3 near Carentan, France, 11 July 1944.

Gun variants:

• T7, standardized as M3.
• T10 - variant with elevation increased to 65 degrees.

Carriage variants:

• M3 - based on M3A1 carriage for the 75 mm field howitzer.
• M3A1 - had stronger trails, made from 1/8 inch plate instead of 3/32 inch.
• M3A2 - was fitted with shield.

Self-propelled mounts

There were two proposals for a self-propelled artillery piece armed with the M3. Neither reached mass production.

External image
105 mm HMC T82. [1]

• 105 mm Howitzer Motor Carriage T38 - based on the M3 halftrack, never built.
• 105 mm Howitzer Motor Carriage T82 (M3 in mount M3A1) - based on the Light Tank M5A1 chassis. Two pilots were built. The project was cancelled in June 1945 due to lack of requirement.

Ammunition

The gun fired semi-fixed ammunition, similar to the ammunition of the M2; it used the same projectiles and the same 105 mm Cartridge Case M14, but with different propelling charge. The latter used faster burning powder to avoid incomplete burning; it consisted of a base charge and four increments, forming five charges from 1 (the smallest) to 5 (the largest). In an emergency, gunners were authorized to fire M1 HE rounds prepared for the Howitzer M2, but only with charges from 1 to 3. M1 HE rounds for the M3 could be fired from an M2 with any charge.

HEAT M67 Shell had non-adjustable propelling charge. For blank ammunition, a shorter Cartridge Case M15 with black powder charge was used.

Available ammunition
Type	Model	Weight (round/projectile)	Filler	Muzzle velocity	Range
HE	HE M1 Shell	/	50/50 TNT or amatol,
HEAT-T	HEAT M67 Shell	/
Smoke	WP M60 Shell	/	White Phosphorus,
Smoke	FS M60 Shell	/	Sulfur trioxide in Chlorosulfonic acid,
Smoke	HC BE M84 Shell	/	Zinc chloride
Drill	Drill Cartridge M14			-	-
Blank				-	-

 

Armor penetration, mm
Ammunition \ Distance, m	0	457	914	1,828
HEAT M67 Shell (meet angle 0°)	102
Concrete penetration, mm
HE M1 Shell (meet angle 0°)	305	274	244	213
Different methods of measurement were used in different countries / periods. Therefore, direct comparison is often impossible.