They will swap into the 9mm SMG without transitional training and never have to master a new weapon which include agencies using the M4 carbine and MP5 SMG. These have entirely distinctive operational distinctions as well as muscle memory from instruction is compromised with the use of different weapon units. https://jasperjwhra.ltfblog.com/26246275/the-definitive-guide-to-colt-9mm-upper