Anyways, ex Soviet/Russian only munitions are still being used. Infamously, they hit a school yard in Homs with horrific results and ISIS was hiding in a structure close by. Source: Russian only (never exported) cluster munitions from 2S4 in Syria.
ex Russian mortar crews are not that hard to come buy...Russia loves mortars and not hard to figure that a contract group, black group, or even SAA/Russian advisors are using 2S4s on groups of ISIS. They (whoever they are) have been using the thermobaric version of the 240mm shell, reportedly, also. . That is a relatively new munition.
3O8 240mm shell below
Excerpt from link:
Syria was one of the few states which received 240 mm heavy mortar systems from the Soviet Union, and has continued to employ them in service. During the Syrian Civil War, M240 towed mortars were used during the battle for Homs in 2012. Evidence of 240 mm mortar projectiles has been very scarce since that time. It may be that the Syrian Arab Army (SAA) had expended a significant portion of its stockpile of F-864 HE projectiles during these 2012 engagements. Some sources have suggested that the renewed use of 240 mm systems is related to increasing Russian support for the Syrian government, however this remains unconfirmed. Regardless, it appears that these munitions were most likely employed by SAA forces [or other forces].