Can you unscrew the bottle without all the air coming out IF you hold the regulator assembly so it does not un-screw there instead? Has anyone replaced the hard to read gauges for better ones (WIKA or digital)?
No, it’s best to drain the air. You could close the regulator down and stop the air. But that would require the gun to be retuned, with the possibly of risking damaging the regulator and/or threads in the body block. It’s super easy to drain and air is cheap cheap. So why risk damaging it.