The gun's design is based on the M101 and leFH 18. The gun's initial model was the SH-1, designed by the Military Technical Institute Belgrade, Yugoslavia, in 1951. It was produced by Crvena Zastava in Kragujevac, now Zastava Arms. Second prototype, also developed by Military Technical Institute Belgrade, in 1955 designated as SH-2 was basis for serial M-56. Serial production started in 1956 Bratstvo Novi Travnik because prior to that in 1945 decision was made by communist government of Socialist Federal Republic of Yugoslavia to move factories from Serbia to other parts of newly formed Yugoslavia in order to develop their industries. Because of that decision in 1951 Zastava Arms factory, then called Crvena Zastava, was partially dissembled (including complete Crvena Zastava factory artillery program with calibers over 20 mm) and together with 250 experts was transferred to Bosnia into new Bratstvo Novi Travnik factory from then Socialist Republic of Serbia to Socialist Republic of Bosnia and Herzegovina to help in Bosnia development at cost of Serbia who in that time was heavy industrialized and had educated technical staff.^[2] The original production version was 28 caliber with a maximum range of 13 km.

Technical data M-56 edit

• M-56 caliber 28
• Weight: Between 2,190 kg
• Min. reach: 2,000m
• Max. reach: up to 14 km
• Muzzle brake: Double
• Min. elevation: -180 mils
• Max. elevation: 1200 mils
• Horizontal limits: 462 thousandths
• Frequency of fire: 6 round/min
• Range M-56: 13.1 km

MTI developed the M56A1 version, with a longer 33 caliber barrel designed to last for at least 18,000 shots, with a stronger breechblock, with recoil systems that allow it to fire modern rounds up to 18 km and a hydro-pneumatic balancer.^[3] The M-56A1 and M09 Soko Self-propelled artillery are offered by Yugoimport and the M-56 by BNT TMiH in Bosnia.^[4][5]

Technical data M-56A1 105mm edit

• M-56A1 caliber 33
• Weight: 2,370 kg
• Min. reach: 2,000m
• Max. reach: up to 18.5 km
• Muzzle brake: Double
• Min. elevation: -180 mils
• Max. elevation: 1200 mils
• Horizontal limits: 462 thousandths
• Frequency of fire: 6-8round/min
• M-56A1: 18.1 km
• Length of barrel: 3500mm

M-09 Soko 105mm self-propelled gun edit

The M-09 Self propelled 105mm gun has direct and indirect shooting capabilities. It can carry up to 60 rounds. It can be mounted on various truck chassis including TAM, FAP, TATRA, KAMAZ and Mercedes models.^[5]

• Range: 15.1 km M02 HE ERBT 18.4 km M02 HE ERFB/BB ^[7]
• Rate of fire: 6-8 rsd/min
• Armour STANAG 4569 level I
• Zastava Arms M87 - 12.7x108 mm for defense
• Integrated fire control system
• An use ammunition developed for the US M101 and M-56A1 howitzer ^[5]

According to the United Nations, some 1,500 units of the M56, in its various models, have been produced and over 200 were exported between 1998 and 2004.^{[8][failed verification]}

The M56 is known to be in service with the following nations:

•   Bangladesh - 56 as of 2016^[update][9]
•   Bosnia and Herzegovina^[10]
•   Croatia^[10]
•   Cyprus - 72 in 1998^[10]
•   El Salvador - 14 in reserve in 1998.^[10] 18 as of 2016^[update][11]
•   Guatemala - 56 in 1998^[10]
•   Indonesia - 10 in 1998^[10]
•   Iran - 20 ^[12]
•   Iraq - fielded during the Iran-Iraq War and Persian Gulf War, former operator^[10]
•   Mexico - 24 with the Army and 8 with the Naval Infantry Corps in 1998^[10]
•   Myanmar - unknown number in used with the Army^[13]
•   Serbia - 256 in 1998^[10]

• America Militar: Photos of the M56 in use
• Máquina de Combate: Yugo Import moderniza el howitzer M56(in Spanish)
• Partner 2013 fair in Belgrade: Soko M09