your M1grand will be found in this folder go
C:/programfiles/Steam/SteamApps/yourname(or)e-mail/DayofDefeatSource/dod/materials/models/weapons/ inside the weapons folder there should be 2 folders V_models and W_models check in theses folders you should see the m1 folder there just delete it, I have all kinds of custom skins and sounds ever need any help i can be found on Vent or in Donner.