Field 122 mm divisional multiple launch rocket system BM-21 "Grad" for three decades is the most massive war machine of this class of domestic production. Designed to engage the open and covered manpower, soft-skinned vehicles and armored personnel carriers in the area of concentration, artillery and mortar batteries, command posts and other targets. Development of the system began May 30, 1960.
Main executor of the system was scheduled NII-147; SKB-203 made launcher; NII-6 solid charges; GSKB-47 combat equipment parts. From the beginning, before the designers had to create a simple to manufacture and use complex, is not inferior to foreign analogues in terms of technical harakteristikam.V as undercarriage was selected all-terrain chassis "Ural 4320" produced by the Ural Automobile Plant.
To simplify the construction of the guide tube, they were manufactured. In the original version of the staffing position of the package guides were shooting across the longitudinal axis of the vehicle. The first test launches showed complete uselessness of such a scheme because of the strong rocking platform after the start of the first shell and reduce the accuracy of shooting.
In addition to turning the guide was reinforced suspension and taken measures to stabilize the body. Now shooting (both single projectile and volley) was made possible not only strictly on the longitudinal axis of the vehicle, but also at an acute angle to it. Two pilot plants "Grad" is factory tested at the end of 1961. From March 1 to May 1, 1962 in the Leningrad Military District passed the state Polygon-service testing of complex "Grad". System "Grad" was adopted by 28 March 1963