As a person wanting to get into the gun industry as a mechanical engineer,
If you want to work for "The Man", don't work in engineering. Engineering does not command the respect anymore that it once did.
Unless you are one of the Peyton Mannings of the engineering world, larger companies tend to abuse their young engineers these days using them as cheap glorified gophers and babysitters for the folks doing the actual work.
Be an entrepreneur and start your own company or go to work for a very small company. While you will work your butt off and be chief cook and bottle washer, the work will be much more rewarding both financially and mentally.
That said, the more experience you have the better your chances although in today's electronic resume world the recruiter is buried in applicants.
Every company and recruiter has different goals but when I was recruiting, I would look for organizational skills, the ability to accomplish projects and goals, leadership skills, a passion for things, and a good basic technical knowledge. Many of these items did not necessarily have to be in the type of business I was working in as many engineering skills are transferable from one industry to another.
I once made the move from a hydrometalurgical refining company to a paper company. Hey, a pump is a pump regardless of what is passing through it.
But, I worked with some recruiters that if you did not have a 4.0 average or better, they would dismiss your resume out of hand.
Good luck.