Lately I've been thinking about joining the Marine Corps. I had a friend who went in and worked a RTE at Quantico for 8 years. Got out and went straight to being head of the Colt custom shop. He is now head of the custom shop for American Western Arms. Anyhow, I love working on guns and would love the have the training that he has and I would also like to have the Marine corps under my belt so I'm thinking about going to the recruiter and seeing if he can give me in writing, a contract saying that I could go in, be trained as an armorer and work at Quantico. Does anyone have any advice on this that they could give me.

Sorry to put a dent in your day but the USMC isn't Burger King, they don't do it your way.  Sounds like your friend joined and got what he wanted along the way, not demanding it before he joined.  You can probably enlist as an armorer, but that's all.  The Marines are about self-sacrifice, commitment, rigor, and discipline, not 'I want this'.  Perhaps you'd be better off wearing the soon to be issued black beret instead of the EGA.

There's the problem. If you think about joining the Corps, then you probably won't join.
So join before you change your mind.

Semper Fi