u/tabletopsocks

I have a set of first stage Apeks DST (swivel turret) with DIN port.

Depending on the valve I'm screwing it into (take doubles 300 bar valve as an example), I often find that

1. I have to screw it in -a lot- to get it to sit correctly without leaking when pressurized, causing pain in my delicate fingers, and/or
2. No matter how tightly I screw, it will not be enough, and it will leak around the handwheel connector/screw when pressurized

I noticed that the threads of the port seem to be machined differently to, e.g., Halcyon/Scubapro/Xdeep, where the latter threads taper off; Apeks threads seem to have the threads more 'square' in the finish. Could this be the cause?

Or am I missing something much more obvious? This is the same on a newly serviced set of regs, so O ring is correctly seated, DIN connector is screwed to correct torque, etc