I have had a synovial cyst sense I was 19 now I am 57 could it be caused from lifting heavy projectiles in the millitary?

Possible. Joints have a capsule arounding then that hold slippery clear goo that acts like oil on a hinge. If the capsule is too weak or the weight on the joint is too heavy, or you used the joint too much, it could bulge into a cyst. However to blame it on a specific activity years ago is hard.