What do you want to do for a PMC? Your degree certainly won't hurt you, but you'll need some kind of operational experience to be seriously considered for an operational job. Think of it this way: would you want to be on a team with you? Or would you rather be out in hell's half acre with someone who has military training and experience, as well as private sector training?

Aside from Blackwater, look into SOC-SMG, Cochise Consultancy, Triple Canopy, Olive Security and DynCorp. Those are some of the bigger names with the longer lasting, more lucratively compensated contracts. The employment page of their websites ought to give you an indication of the kind of folks they're looking to deploy.