sounds like a gun cleaning issue.
I've read a lot of posts about differnt guns, caswells gun is great, what others you guys use.
If you dont clean her out you will get speckles/spots from others.
Unsrew the small air adjusting screw on the bottom and blow the gun out real good from that point, the pick tube and exit(tip) for at least min. each and alternate the blow out/cleaning process in each whole for a while.
May take a few minutes, but I can go from white to black with no problems doing it this way.
Is there a faster color change with other guns
?