gravity gun?

I talked with a member on here that does a lot of body work and he too said he had a HF gun that has had a lot of use (YEArs and many cars!), and works great.
of course, it helps to adjust it just right!? gravity guns can be bought pretty c heap. I have 4 cars of mine i'm working on. not an overnight get done thing!
I cleaned my old siphon gun but it needs more. I need to get a brush for it. it is 20-25 years old and been sittin 8-10 years for sure. it haed an air pressure control and small water trap at gun. they were full of dirt dauber dirt!!! LOL