You really want the MP5 to be the end goal for cop? Seriously?
The MP5 isn't some godly new weapon, it's just a silenced MP7 with reduced damage, reduced accuracy, faster movement speed, and no tracers.
Especially for a cop, the MP5 seems useless. When you're a cop, there won't be a scenario where you need to shoot someone without making noise or firing tracers, because unless you're breaking the rules, you're probably being shot or were being shot. (I guess you could try to kill a bounty as a cop but I don't know why you'd want to do that over cuffing and jailing them.)