Been meaning to hop on this post. Chris was most def former military. Here is the evidence I cite to.

The time he took the crew out to the brook to shoot. He was teaching them like a gun instructor.

Second, is when him, Snoop and Micheal simulated stalking each other with the paint gun.

Chris had the body language of someone from the military. Also he had a rule to get to the job hours early so that no one can set up on him when he was setting up on them.

Chris was a great character.