In 1940, the Russians adopted a new rocket launcher with 16 130mm M-13 missiles. This was the BM-13-16 "Katyusha". Built on many trucks, the BM-13-16 ingame had be built on the Studebaker US6 "Studer" truck and saw his debut in the war in april 1943.
(* = the name BM-x-y are used for ground vehicles with the Katyusha rockets. 13 is for the rocket the (M-13) wich nearly show us the diameter. 16 are the count of rails. In particular, BM-13-16 is a vehicle which fires M-13 missiles and has 16 rails)