These are the raw, uncompiled combo arms "c_arms" models for HL2, CS:S, and DoD:S. Originally done by Inaki for the Garry's Mod 13 update, Inaki gave me the raw source files so that I could share them around.
The arm meshes for HL2, CS:S, and DoD:S are included.
The included readme files for each game dictate some minor issues or bits that could be improved upon.