In May 2017 Russia delivered (by ship) another 21 M30 122mm howitzers to Syria. These towed guns were widely used during World War II and production continued until 1955. They are still used by over 20 countries because they are cheap, reliable, easy to operate and rugged. Russia provided many of them to Arab customers during the Cold War. These weapons are still cheap as Russia can afford to give them away because at the end of the Cold War Russia demobilized most of its army and ended up with 4,000 M30s in storage. There was still demand for this old reliable, even though an improved version, the D30, entered production in 1963 and is still being produced. Used M30s were cheap (often free to favored customers) and that often came with offers of war surplus 122mm ammo that was being given away (because a lot of it was well past its “use by” date). For a customer like Syria less accurate but free 122mm ammo was fine because since 2011 the Syrian army has used its 122mm guns mainly against residential areas in order to chase away pro-rebel civilians or convince them to make peace. For more accurate artillery fire Russian sent some of its most modern rocket systems, some of them using satellite or other guidance systems. These were used against precise targets in order to test these new weapons and, when they worked, to serve as an aid in selling them to customers who needed it and could afford to pay.
The M30 is a three ton, towed gun that entered production in 1939 and over 19,000 were eventually built. China began building an M30 clone in 1953 and before production ceased in the 1980s some 10,000 were delivered. During World War II the M30 comprised 31 percent of Russian field artillery.
The D30 is a four ton, towed weapon with a range of 15 kilometers (or more, with special ammo) that has a longer barrel and more effective mechanical components. It can use the same ammo as the M30 but often uses more expensive modern ammo that has longer range (22 kilometers, twice that of the M30) and is more accurate. The D30 was used as the basis for numerous self-propelled guns built during the Cold War. But if all you need to do is kill civilians the M30 will do. When the civil war began in 2011 the Syrian Army had about 750 Russian towed 122mm guns, 20 percent of the M30s and the rest D30s.