What is the model name for the m16?

Exactly what the title suggests. I need to know the model name (and location, hopefully) of the M4a1. Please and thanks in advance. I didn’t find this on a search from Google, or these forums, so I tried.

I checked its lua file and found

SWEP.ViewModel			= "models/weapons/v_rif_m4a1.mdl"
SWEP.WorldModel			= "models/weapons/w_rif_m4a1.mdl"

The M16? Now where have you seen one of those in Gmod?