This is a historical page that documents Weapons, Gear, Modes, Maps, Sales, or Events that are no longer available, and as such, information should only be added.
The Default Primary Weapon Change - MP5A4 is a Special Item that can be bought in the Black Market. When bought, the Default Primary Weapon (which is the M16A3, unless you bought another default primary weapon) would be ultimately changed into the MP5A4, thus allowing you to keep it forever.
Although this may sound like a good idea, it costs a whopping 33000 NX (an equivalent of $33 USD), although it makes sense for it allows the player to not worry about the weapon expiring and allows them to play less often and keep their GP from diminishing.
The price has been found to have a lot of complaints, so it has been lowered to 24,900 NX, an equivalent of $24.90 USD.
As of the 2-3-10 Patch, Default Primary Weapon Change - MP5A4 along with the other Default Weapon Changes have been removed from the Black Market and are no longer available.