SV, what i emant was, half life itself doesnt really use smoothing groups,
it unweldes verts along the edges of the smoothing groups, so ingame and in hlmv it appears as if the smoothing groups are still there but they really arent,
try this decompile ANY esf model that you think has smoothing groups, even your own, import the reference smd, now select all of the verts and weld em, notice how all of your model is in one smoothing group again, its cuz like i said when exporting to smd it automatically unwelds the verts along the edges of the smoothing groups you had set in milkshape,
it still looks like they are there but itsjust unwelded verts, not smoothing groups giving it that effect after you export it to smd, (i hope i explained it better thattime)