Bringing Work Home with Me

[Eyesinthesky]

Morning,
I am currently out and about on an extended "vacation". When I get back I'd like to replicate as closely as possible what I use at work and since I have nothing but the utmost respect for the folks here, I figured I would bounce my ideas/get some input here.
My reason for doing this is that in the event of something happening I don't want to have complete confidence in my abilities to handle my weapons. Unfortunately I don't get many opportunities to shoot with my squadron. I already purchased a Beretta 92FS and shoot with that frequently when my schedule allows. When I get back I'd like to build an M-4(gery) as close as I can to what I get issued. I've already tracked down the optic we use so my question is which version of the hundreds on the market are closest in terms of quality/performance to the M4 I get issued?

As a forewarning I just came off shift so my search-fu may not be up to par. Thanks for your input in advance.