I applied through a recruiter. The process took 3+ months. I interviewed at US Marine Corps (San Diego, CA)
Interview
There is a 3 month mandatory interview process. This process is to assess your mental and physical capacity to operate under stress. It is 24 hours a day. But don't worry. The USMC will provide "3 hots and a cot". You also get some time on the range but not nearly enough.
Interview questions [1]
Question 1
This is performance based. "Can you get up out of bed get dressed, shave, make your rack, and be out the door going to chow in 5 minutes?"
I applied in-person. I interviewed at US Marine Corps (Washington, DC)
Interview
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.
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!".