I have to do this for some reason to get access to the GD's website. Interview process, walked into the recruiting office and said "sign me up". Recruiter was a friendly guy, said "Ok!".
J'ai postulé en personne. J'ai passé un entretien chez US Marine Corps (Washington, DC)
Entretien
It was a very easy but a lot of paperwork. Interview consisted of medical check, mental health check, and a drug test. There were multiple tests that had to be taken on a computer and a very long background check.
This was a tough interview process and the screening was rigorous. It will take a long time. I recommend getting started early. This is a long term commitment. You need to be ready for it.