Nah, sorry mate. If you look carefully, it says "hahathereisnocode" I guess you'll just have to do the whole battlefield veteran thing to get the gun. Besides, it isn't all that great, runs out of ammo real quick and does little damage. If you really want it though, just rent an old Battlefield game and sign up on EA, etc.
F2000 you missed the last 0 :D
Usually not, but some guns do have interchangeable magazines. For example, the Type 97, FN200, Tar-21, and L85 can all use M4/M16 magazines, but there is always the problem of some magazines not fitting quite right or not feeding well.