Default Primary Weapon Change - M4A1

The Default Primary Weapon Change - M4A1 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 M4A1, thus allowing you to keep it forever.

Although this may sound like a good idea, it costs a whopping 35000 NX (an equivalent of $35 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.