The BM-21 "Grad" is a self-propelled 122 mm multiple rocket launcher designed in the Soviet Union. The system and the M-21OF rocket were first developed in the early 1960s. The complete system with the BM-21 launch vehicle and the M-21OF rocket is designated as the M-21 field-rocket system. The complete system is more commonly known as a Grad multiple rocket launcher system.
The M-21 field rocket system with a BM-21 launch vehicle (122 mm multiple rocket launcher (MRL) system) entered service with the Soviet Army in 1963 to replace the aging 140 mm BM-14 system. The launch vehicle consists of a Ural-375D 6x6 truck chassis fitted with a bank of 40 launch tubes arranged in a rectangular shape that can be turned away from the unprotected cab.
The best way to the BM-21 is to be in range to support your team.
Find good position to fire from, because if you start firing your rockets, you will be spotted very easily by the smokes from your rockets. If you fire to often in the same area, you will be hunted soon.
The reloading process takes quite some time, so the best way to use the artillery, it is better to have Forward Operating Base nearby, where you can resupply.