Thanks Mark. I've actually got somewhere around 10 guns in the shop. Coming from an automotive paint background, I've accumulated quite a few over the years. The main ones that I use though are as follows:
Sharp Cobalt Gravity HVLP (1.4 needle)
Binks Touchup Gun (non-HVLP)
Binks #7 (non-HVLP)
Binks Wren Airbrush setup
For the majority of my burst finishes...including the guitars here.....I mainly just use the Sharp and the Binks Touchup gun. I can dial the Binks down to a very tight pattern and when spraying the bursts, really concentrate tightly on the very edges to build darkness before I actually open it up a bit and allow some inward blending overspray for the burst. When I need a really tight and small burst around the very edge such as a very thin black edging, I'll use the Binks Wren most of the time. It's slower but provides the small, tight pattern that I need for that purpose. From there, it's really just a matter of gun angle. To get a very dark edge, alot of times I'm angling the gun outward and the majority of the spray material is actually missing the guitar. But since I'm almost dry-spraying in these cases, it's not a big waste. One other thing I'll mention that helps to give me good results......when I'm done with my bursting, I don't allow any drying time. I immediately burn it in with several heavy coats of reduced clear. Doing this helps to melt the blending in before it's had time to cure/harden and leave a textured finish.