Kevin_M, the door gunners that augment the helo crews are mostly infantry (reg and reserve) and a few tankers tossed in. These folks were canvassed by their units (well, most units did, some just did not bother) and though we (the Air Force) had minimum requirements, we got some that did not meet them. It was preferred the guys had at least one tour under them.The army does not like giving up experienced soldiers to us, though it is for the most part.
So, a newbie getting this is slim though we do have a couple of privates but it is the exception. Or you could go Air Force as an AVN tech for 4-6 years, then remuster to Flight Engineer. Pays better and you get to wear a wedge...nothing drives the guys in green crazy like a zoomie wearing a wedge with a cadpat jacket on ;D