User blog comment:JoeRamirez/Call of Duty Modern Warfare 3 Weapons Wishlist./@comment-4056988-20110612230518/@comment-71.139.1.158-20110613015804

MP5A3 is a advanced version of the MP5 since it comes with a handgrip ( not grip, handgrip. Like the one where you hold a gun with your non-trigger hand). A meaning 'Advancement' makes sense.