Vanilla sounds and textures were used to keep file size down. The M2 is moddable with only the Extended Magazine. (Assault Carbine mags, Varmint Rifle Night Scope) The Carbines are available from Chet's General Store, Novac Gift Shop, 188 Trading Post, and the Crimson Caravan Company. The M3 Carbine is moddable with an extended magazine as well as a night scope. The M1 was built from 'this machine' so any retex mod for it will work on this mod as well.
This mod adds an M2 and M3 Carbine to Fallout New Vegas.