Distinctive features of the D-30 include its low mobile mounting and above-barrel recoil system. The three-legged mobile mount is unusual for field artillery, with stabilizers that are clamped together for towing and deployed when in action. A large tow linkage is fixed to the muzzle; in transport the barrel serves as a trail. Similar mounts were a feature of several pre-war (1931–1935) universal (both field and anti-aircraft) guns designed by Leningrad's Kirov Plant (L-1, L-2 and L-3). Other examples were the 1939 French 47SA39 APX, and 1943 German light field howitzers designs by
Skoda and
Krupp; neither entered service. The
Bofors L28 Light Field Howitzer 4140 was similarly arranged with four legs and did enter Swedish service. The 1930s-designed British
2-pounder anti-tank gun was another piece featuring a three-legged mounting. Compared to the M-30, the new howitzer had a significantly longer 35 calibre gun barrel, just short of being a gun-howitzer by Soviet definition. Like other guns of the period, it had a high efficiency
muzzle brake; this improved muzzle velocity by to a maximum of for HE, and with an increased maximum range by beyond the similar M-30. The maximum range was better than the M1942 at . Weight increased by over the M-30, to ; the D-30 is over twice the weight of the 76 mm
M1942. Accuracy improved, with mean error at about dropping from with the M-30 to just . Effective stabilisation length is a fundamental aspect of a gun mount, and legs 120° apart need to be longer than those with a smaller angle. The D-30's design minimises this problem in several ways.
Trunnions are close to the ground, as a result of placing the recoil system and cradle above the barrel. The trunnions are also at the very rear of the breech; this maximises the recoil space when firing at higher elevation angles. Their rearward position also pushes the recoiling element forward on the mount, maximizing relative rearward span of the stabilizers and so stability during recoil. Additionally, there is a very efficient muzzle brake, which absorbs about half the recoil. There is no mechanism to reduce recoil length as the angle of elevation increases. Some of the design decisions have a price. The muzzle brake produces about twice the
overpressure in the area around the gun than is acceptable to Western armies, and is the reason it is often seen being fired with a long lanyard, which reduces rate of fire. Furthermore, the maximum elevation angle is restricted to 18° (early versions) or 22° (later versions) when the breech is over a trail leg. This is enforced by a mechanical cam that prevents the piece firing for about 60% of the total top traverse, and limits range to about , with full maximum range only possible in the central arc of about 48° between each pair of legs. The extreme rearward location of the trunnions means the elevating mass is unbalanced, requiring a strong balancing mechanism to enable manual elevation. To do this, the D-30 uses compression balancing gears. A central jack is powered by hand-operated hydraulics. This jack is lowered while the wheels are raised to permit two of the stabiliser legs to be swung 120° rearwards. The mounting is then lowered, and the ends of the legs spiked to the ground. This mounting provides for quick traversing to fire in any direction. The pair of large tires are suspended on a single trailing arm; the maximum towing speed is on the road. As was normal in Soviet designs, the tires were filled with foam. Initially, the D-30 had no brakes and no seat for the layer—non-essential luxuries. A
sliding block breech was adopted instead of the M-30's pre-1914 screw pattern, giving a slight increase in the rate of fire. It is a semi-automatic vertical sliding block breech, with a tied jaw; the block moves down to open and opens automatically ejecting the empty cartridge case as the recuperator forces the gun tube back into battery after a round is fired. The design is closely related to those of breeches on other Soviet post–World War II guns and howitzers. The non-reciprocating sights are standard Soviet pattern, designed for one-man laying. Included are a direct fire anti-tank telescope, a panoramic periscopic indirect-fire sight (dial sight) in a reciprocating mounting, an angle of sight scale, and a range drum for each charge engraved with the range (distance) scale. The elevation leveling bubble is mounted on the dial sight mount. 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. Soviet howitzers used different ammunition to guns, although there is some compatibility. In the case of ammunition for the D-30, the standard howitzer shell weight of was retained, with a metal cartridge case holding variable propelling charges. Cartridge and shell are loaded separately; this means that the shells have to be hand-rammed by a man to the right of the breech with a ramming rod. The D-30 could fire the older M-30 ammunition; however, new shells were also introduced, eventually including a
rocket-assisted projectile with a range of . The M-30's range of propelling charges, comprising base and eight increments, was replaced by a new set comprising base and four increments; single base propellant was retained. A more effective
High Explosive (HE) shell was developed, as well as smoke, illumination, and chemical filled projectiles. In keeping with Soviet doctrine, the anti-tank role is important; there is a
HEAT shell capable of penetrating of steel armour plate. The maximum rate of fire of the D-30 is 6–8 rounds per minute, and about 75 rounds per hour. There is disagreement as to whether this maximum rate of fire is achievable for indirect fire. Based on reloading speeds of similar guns using separate charges, solo re-laying, and given a stable emplacement, semi-automatic breech and no long lanyard, (examples are the
25-pdr and
L118), and assuming concurrent lay adjustment during reloads, then it probably is when in the hands of a competent detachment. However, 5–6 rounds per minute may be more realistic with a poorly trained gun crew. The D-30 is noted for simplicity of maintenance by its users; reputedly, there are no special tools, and all jobs can be done with a wrench and large hammer. However, like any other gun, routine maintenance is essential, and Western troops in Afghanistan have reported Afghan operated D-30s having problems with shells sticking in the barrel due to lack of cleaning. The D-30 is known as
hehtaaripyssy (literally "Hectare Gun") in the Finnish military, as the scatter area of the shrapnel of the shell is approximately one
hectare.
Self-propelled versions •
2S1 Gvozdika was developed on basis of
MT-LB tracked vehicles that were often employed by Soviet forces for towing instead of trucks. Combining the gun D-30 with the chassis of the
MT-LB, the
2S1 Gvozdika was made. This was the first Soviet enclosed turret self-propelled artillery gun, going into service in the early 1970s. The
2S1 is very light and mobile, and amphibious without preparation. Good mobility and the quick reaction abilities of the 2S1 enhance the flexibility of the D-30, reducing its vulnerability in maneuver battles. •
Sora 122mm Most modern self-propelled version of the D-30J with automatic loader, inertial navigation system (INS) and fire control system, mounted on a modified
FAP 2026 chassis designed by
Military Technical Institute Belgrade. • SH-2 Chinese wheeled version developed by
Norinco. It has a modern fire control system and howitzer is elevated by electric motors. •
PLZ-07 Chinese version of tracked D-30 122 mm. It has NBC protection system, night/day driving vision, firing control system. • Semser developed by Israel's
Soltam under contract to the Kazakhstani Ministry of Defense, manufactured by local Kazakh companies. Has an integrated automated command and control system, provided by Soltam and
Elbit. Is based on
KamAZ-6350 8x8 chassis. Other countries have produced self-propelled versions of the D-30 by mounting the gun on tracked or wheeled vehicles at the disposal of their armed forces. Most such vehicles do not have any complex fire control system and are manually loaded and elevated. Cuba, Sudan, Laos, Syria, and Egypt have produced such simplified variants. Post 1973, Syrian and Egyptian armed forces fielded D-30 guns fitted to the hulls of obsolete
T-34 tanks, similar to Israeli conversions of
Sherman hulls. This rather crude modification improves the speed of divisional artillery, allowing for the ability to match speed with frontline mechanized forces. A major drawback is the lack of protection for the gunners.
Variants •
2A18 or
D-30 – basic model, as described. •
2A18M or
D-30M – new double baffle muzzle brake, square central base plate, towing lunette assembly. •
2A18M-1 or
D-30M-1 – with semi-automatic loader. Prototype. •
D-30A – modified recoil system, new muzzle brake. •
2S1 Gvozdika self-propelled version. •
Type 85 or
D-30-2 Chinese self-propelled version of the D-30. •
D-30-3 – Chinese upgrade of the
Type 56 field gun with weapon. •
Type 86, variously,
Type 83,
Type 96 – Chinese licence-production or derivative of the D-30. •
D30 RH M-94 – Croatian built version, new muzzle brake, redesigned trail, improved
hydraulic brake. •
D 30-M – Egyptian license version of the D-30. •
SPH 122 – Self-propelled version, mounted on a modified
M109 chassis. •
T-122 – Self-propelled version, mounted on a modified
T-34 chassis. •
HM 40 or
D-30I – Iranian version. Is believed to be an exact copy with no visual or functional changes. •
D-30J – Yugoslav version of the D-30, it features a simplified muzzle brake, a hydraulic firing jack to ease and speed up combat operation, and maximum firing range is increased from to •
Saddam – Iraqi copy of the D-30J produced by Saad 5 (Saddam Engineering Complex). Production was halted after the
Gulf War •
D-30JA1 – Improved Serbian version – further development of D-30J. •
Sora 122mm – Self-propelled version of D-30J •
M-91 "Mona" – Yugoslav variant with the ordnance of the
MT-12. Prototype only. •
Khalifa-1 – Sudanese licensed version of the D-30. •
Al Thahadi - Iraqi-made version of the D-30. ==Ammunition==