I have a gravity feed spray gun.I am spraying epoxy primer.I am getting dry spray on the outside of the pattern.Do I need to adjust the paint volume or what is causing this? Also what affect would the air adjusting screw on the gun have? Thanks!

Could be your fan is too big, too much air pressure or you need to adjust for more fluid
Try doing test patterns with thinner in the gun first and play with the controls till you figure out what they do.