Hvlp pressure

Forget the 10 psi at the cap. You have no real way of measuring it. Either indicated on the handle of somewhere in the instructions that came with your gun there should be a pressure stated at the gun inlet to give you the 10 psi at the cap. On one of my guns, this number is 29 psi. You need to find out what this number is for your gun.

The next thing you should do in to tee in a pressure gage at the inlet to your gun. I know it's bulky but it is necessary if you want to do it properly. Then adjust your wall regulator to whatever is necessary to yield the required pressure at the gun inlet. Do this with the gun trigger pulled. The pressure at your wall regulator will be significantly greater due to pressure drop in your hose and fittings. Not to worry. It's the actual pressure at the inlet to the gun while the trigger is pulled that counts.

Rod