What is the average salary of a weapons engineer?

I have recently been looking into job opportunities for the near future and one that has interested me the most would be a weapons engineer. I would be believe that this would be a job working for a company such as HK, Barrett, MagPul, Remington, and other alike companies. I was wondering if anyone had any experience with these jobs and could tell me a little more about them, what kind of schooling I should do to prepare for them, and what the average salary would be for them? Any help would be great.