ghostfish1
Depends on what country you're in, and who you know, and what you want to do - the field is pretty wide, even having said experimental / production flight testing.
There are some R&D facilities in many countries that might welcome civil experience as being more valuable than you might imagine. A disciplined approach to describing your flying background is definitely needed- anything in particular that you have developed, written, etc. to move the industry forward?
Otherwise, your ability to get in depends on the country you are in. Most manufacturers require TP experience, a very large hurdle, but some will take you with an engineering or science degree and develop you from there.
Contact me off-line if you want to talk about it some more.