M-46 52P482 130-mm Towed Gun - Design
The 130-mm towed gun M-46 is designed to destroy earthen defensive structures, combat self-propelled artillery and heavy tanks, artillery, mortars of the enemy, suppress manpower and tanks in the area of their concentration, and shell the enemy's rear. In terms of its tactical and technical characteristics, the M-46 can be placed on a par with guns designed 30 years later, such as the 2A36 (Giatsint) and 2A65 (Msta).
It is a true gun, being unable to fire much above 45° and having a long barrel and a single propelling charge. In contrast, most Western field guns of this period had a dual high and low-angle fire capability, a gun-howitzer. It has a 39 caliber barrel with a tied jaw horizontal sliding-block breach and a 'pepperpot' muzzle brake. The latter is not notably efficient, but subjective reports suggest that it is quite effective in reducing muzzle flash. The hydro-pneumatic recoil system comprises a buffer below the barrel and a recuperator above the barrel.
The 130-mm field gun M-46 is distinguished by a long, thin tube with a cylindrical, perforated (pepperpot-type) muzzle brake and has a hydropneumatic recuperator and a recoil cylinder located above and below the tube, respectively. When in travel position, the tube is withdrawn from battery to reduce the overall length of the weapon, and the recuperator above the tube may then be hidden from sight by the rearward-angled, winged shield. The gun has a manually operated horizontal sliding wedge breechblock and fires case-type, variable-charge, separate-loading ammunition. It has night direct fire sights (IR and/or passive in nature).
The gun is mounted on a two-wheeled split trail carriage with large sponge-filled rubber tires on each of the single wheels. For travel, it is provided with a two-wheeled limber and can be towed by a truck or armored vehicle.
The M-46 fires separate-case loading rounds. The main types of projectiles are high-explosive fragmentation and armor-piercing tracer; special types include illumination (with a parachute flare), sighting-target designation (with a smoke-forming composition), and chemical (with combat chemical agents). The charge is variable. The Firn-1 guided artillery weapon system has been developed for the M-46. The firing range of the guided projectile reaches 24 km.
High-explosive fragmentation shells of the 53-OF-482-M brand have a maximum projectile flight distance of 27.5 km at a speed of 930 m/s. The projectile itself weighs 33.5 kg, 3.6 is the weight of the explosive, the weight of a full shot is slightly more than 59 kg. ZOF 43 shells have other characteristics at the same firing distance. This projectile has an explosive of 4.2 kg. The other parameters are the same. For comparison, 122 mm high-explosive howitzer shells weigh approximately 22 kg and 2.5-3 kg of explosive, depending on the modification. 152 mm shells weigh 41-44 kg and have 4-6 kg of explosive on board.
Compared to 122 mm shells, 130 mm shells are a third heavier. The weight affects the work of the calculations. Someone may object that 152 mm shells are even heavier. However, these shells have a higher efficiency of high-explosive and fragmentation effects, and the guns have different rammers and an automated loading system.
In the 1960s, a rocket-propelled projectile was introduced, first used by Syrian forces in the 1973 Middle East war. The Iranian army, armed with the M-46, uses a locally developed projectile with a partial gas bleed from the loading compartment, which increases the firing range to 37,000 m. The same projectile is produced by the Chinese company Norinco, with a range of 38,000 m. Various types of ammunition for the M-46 are produced in 12 countries, including Finland and South Africa.
The armament includes an armor-piercing projectile that can penetrate 250 mm of armor at a distance of 500 m. However, such a projectile is enough for an infantry fighting vehicle or armored personnel carrier at any flight distance. Oddly enough, it has 125 grams of explosive. However, this is a tracer charge.
The long (7.6 m) barrel of the M-46 was equipped with an original muzzle brake, nicknamed the "pepper shaker", and a horizontal wedge mechanism of the breech. The recoil brake includes a hydraulic buffer; above and below the barrel is a hydropneumatic recuperator.
The barrel moves in a clip-type cradle. Anti-recoil devices include a hydraulic recoil brake and a hydro-pneumatic recuperator mounted below and above the barrel. The recoil is variable to prevent the breech from hitting the ground when firing at high elevation angles. The lifting and rotating mechanisms are of the sector type. The columns of the balancing mechanism are installed on the right and left sides of the cradle. The upper and lower carriage mounts are connected by a combat pin. The lower mount is equipped with two sliding box-shaped beds with winter and removable summer openers. The combat travel includes two wheels with rubber tires, torsion suspension and a wheel brake. When converting the gun from the traveling to the combat position and back, the crew uses hydraulic jacks to lift the beds, a winch (on the right bed) to pull the barrel to the traveling position and roll it to the combat position. However, the time it takes to move from the traveling position and back is long, and in this respect the M-46 is inferior to, say, the 122-mm corps gun D-74 of 1954.
The long barrel enables a substantial propelling charge by providing more length in which to achieve 'all burnt and hence projectile acceleration space and thus achieve its 930 m/s muzzle velocity. The barrel is mounted on a split-trail carriage, with deep box section trails and foam-filled road wheels on the ground when firing and 50° of the top traverse. The small shield protects little more than the sights, possibly including from the effects of muzzle blast, and some protection from machine-gun fire in anti-tank engagements. The gun has long and robust trails to provide stability when firing and a large detachable spade is fitted to the end of each when the gun is brought into action.
Non-reciprocating sights are standard Soviet patterns, designed for one-man laying. Included are a direct-fire anti-tank telescope, a panoramic periscopic indirect-fire sight (a dial sight) in a reciprocating mounting, an angle of sight scale, and a range drum engraved with the range (distance) scale, coupled to a mounted elevation leveling bubble. The range drum enables the standard Soviet technique of semi-direct fire when the piece is laid visually on the target and the range set on the range drum. An APN-3 was later provided for direct fire at night in place of the day telescope.
The sighting devices included the S71-35 mechanical sight (later S71-96) and the PG-1 gun panorama (PG-1M); for direct fire, the OP4M-35 optical sight was used, then the OP4M-96. The Luch-S71 M device was used to illuminate the sighting devices at night.
The gun is towed using the front end. At first, the medium tracked tractor AT-S was used as a tractor, and later other tractors were used.
For travel, the gun is towed via a two-wheeled limber fitted to the end of the closed trails, with the spades removed and carried on each trail. Simple jacks on the trails just behind the main wheels are used to lift and support the closed trails so that the limber can be connected. The barrel and recuperator are pulled back between the closed trails and locked in a traveling position. There is a large bicycle chain arrangement on the right trail for this, and a compressed air cylinder, charged by the gun firing, is used to bring the barrel forward when the gun is brought back into action.
It can be towed by a variety of vehicles: AT-S, ATS 59 and unarmored artillery tractor M1972, as well as the armored tractor AT-P.It takes about four minutes to bring the gun into action, the normal detachment is eight or nine strong. Propelling charges are in metal cartridge cases and loaded separately from the projectile. Projectiles originally included HE fragmentation, Armor Piercing solid shot, smoke, illuminating, and chemicals. HE shells weigh some 33 kg. Illuminating shells have a substantially lower muzzle velocity. APHE and extended-range shells were introduced later. The maximum rate of fire is probably 6-7 rounds/minute, and about 70 rounds/hour. The standard Soviet unit of fire was 80 rounds.
The first issue guns had a barrel with a casing and a free tube and a screw-on breech. Later ones had a monoblock barrel connected to the breech with a coupling. A muzzle brake is screwed onto the muzzle of the barrel. The barrel is locked by a horizontal wedge breechblock, opening to the right, without automation. The breechblock contains a striker-type firing mechanism. There is a safety device against premature release and an inertial safety device in case of a prolonged shot.
The M-46 gun crew is provided limited frontal protections by virtue of a frontal V-shaped shield (approximately 7-mm thick). Otherwise, the crew, ammunition supply, and equipment are vulnerable to casualties and damage from small arms fire, artillery fire, and bomb shrapnel.
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