Head= Leatherneck from Joe Mech
Torso=Alpine
Arms, lower legs= Faces
Waist, upper legs= ??

M16= Joe Comic 3-pack
AK= JvsC
Pistol= JvsC
Back pouches= bbi
Snake= Coil Crusher
Croc= Croc Master

From Metalgearsolid.com:

Member of special forces unit "FOX". Nickname "Jack".
Last apprentice of The Boss. Was taught by The Boss one-on-one all about combat, destruction, espionage, pyschology, etc. from in the 50s. Created CQC with her.