M4A1 is a late modification of the M-16. Replacing the standard m4 with an improved one, both in terms of textures and the model of the weapon itself. (This is an envelope from CS 1.6) To be precise, the standard is not the same - this is a mod on m4 in CS 1.6, and I just made an m4 converter in GTA SA. Author information: Model: Mole/sas.stu/IronClad texture: Wannabe /-X-/ SixShooter.