8 Inch Self Propelled
Specification from 1963
30 August 1963 TM 9-500
CANNON, 8-INCH HOWITZER: M2A1E1; MOUNT, GUN-HOWITZER: M158;
MECHANISM, FIRING, CANNON: M35
Model Line item No. Federal stock No.
Cannon Mount Mechanism
CANNON, 8-INCH HOWITZER: M2A1E1 with MOUNT, GUN-HOWITZER: M158, RAMMER AND LOADER ASSEMBLY ORD No. 10898300 AND MECHANISM, FIRING, CANNON: M35, provides the major armament for the HOWITZER, HEAVY, SELF-PROPELLED: 8-inch, M110 (T236E1).*
The 8-inch howitzer cannon M2A1E1 consists of a barrel assembly screwed into an internal thread In a breech ring and locked in place by three screws. The barrel assembly is of monobloc (one-piece) construction. The chamber and bore are chrome-plated. Bearings for support and alinement in the mount are provided by longitudinal rails attached to three hoops shrunk on the jacket. The rear half of the breech ring is lined with a breech ring bushing to accommodate an interrupted screw-type breechblock and a bottom lug for connection to the recoil mechanism.
The gun-howitzer mount M158 includes the recoil mechanism of the hydropneumatic variable recoil type, which controls the forces created by firing and checks the movement of the recoiling parts gradually, to avoid displacement of the vehicle, and also returns the recoiling parts into their original position. The major components are the recoil, counterrecoil, and recuperator cylinders, contained In the gun cradle, and the replenisher cylinder.
The rammer and loader assembly operates to lift a projectile from the rear or left side of the vehicle, position it for ramming, and ram it into the cannon chamber. Hydraulic power for operation is obtained from the vehicle hydraulic system. Operation can also be accomplished manually by means of handcranks.
The firing mechanism is a percussion type and is operated manually by a lanyard.
Differences among models
Data plate location
Mount, M158 Standard A (OTCM 37684)
Cannon complete 10,240 lb
Barrel assembly 8,490 lb
Breech mechanism 1,750 lb
Tipping parts 14,740 lb
Tube 16 ft, 10.5 in.
Cannon 17 ft, 9 in.
Length 164.8 in.
Number of grooves 64
In calibers 25
Diameter 8 in.
Breechblock interrupted screw, stepped thread
Operation manual, by lanyard
Weight 4,500 lb
Weight (approx) 3,925 lb
Number of recoil cylinders 1
Length of recoil:
Normal high elevation-28 to 30 in.
Maximum low elevation-68 to 70 in.
Type of recoil oil FSN 9150-255-4443 (OHC)
Oil capacity 15 gal
Replenisher 2 pt
Recuperator 2 pt
Elevation (max) 65 deg
Depression 0 deg
Turret traverse (right or left) 30 deg
Traversing and elevating operation manual or hydraulic
Type HE, dummy
Muzzle velocity 1,950 fps
Range (maximum) 16,930 meters
Allowable recoil (variable) 70 in.
Rate of fire:
Normal 1 rd per 2 min
Maximum 1 rd per 1 min
Maximum number of rounds fired consecutively at max rate
Maximum powder pressure permitted
Average accuracy life rd
Sighting and Fire control:**
Installed on self-propelled howitzer M110 prior to issue:
MOUNT, TELESCOPE: direct fire, M138
MOUNT, TELESCOPE: panoramic, M137 (T186E3)
Boxed and stowed on self-propelled howitzer M110 prior to issue:
FUZE SETTER: M26 and M27
LIGHT INSTRUMENT: M52
PERISCOPE, TANK: M17
POST, AIMING: M1A2
QUADRANT, FIRE CONTROL: elevation, M15 (T23E2)
QUADRANT, FIRE CONTROL: gunner's, M1A1
REFLECTOR, AIMING POST: clear, M1
REFLECTOR, AIMING POST: red, M2
SCALE. GRAPHICAL FIRING; M71
SCALE, GRAPHICAL FIRING: site, M72
TELESCOPE, ELBOW: direct fire, M116C
TELESCOPE, PANORAMIC: M115 (T146)
Basic Issue Item: See TM 9-2300-216-10
PROJECTILE, 8-INCH. DUMMY: MK1
PROJECTILE, 8-INCH. DUMMY: M14
CHARGE, PROPEI,LING, 8-INCH, DUMMY: M4
PRIMER, PERCUSS10N INERT: MK2A4
Reference: TM 9-2300-216-10
*For characteristics and data, see item in section 23.
**For characteristics and data, see Item in sections 12, 14, 13, and 27.
Thanks to Lynden T. Couvillion (Couvi) for sending in the data.
Thanks to Charles E. Stephenson for preparing the information.