 The users were not enthusiastic at the very beginning for several reasons, such as the fact that barrels had to be modified.During the '80's, the cartridge became the perfect caliber to be used for all those automatic pistols designed for military cartridges (i.e.9x19mm) all over the world that are frequently forbidden for civilian uses; for this reason "Israel Military Industries" (IMI) started to use 9x21mm.During that period IMI got permission to import the UZI Defender (also called Micro Uzi) into Italy chambered for 9x21 IMI.