This shell has been lately widely used by Syrian rebels and is nicknamed midfa` jahannam (the latter word is an old Ethiopic word which means hell and appears in the Qur'an). It is basically another version of the regime's barrel bomb but has a gas canister (which can be filled with explosives). This shell I am told has a terrible accuracy and falls in a quarter--as far as pinpointing is concerned. Has there been one article in the Western press about them?
