Odd because we aren’t seeing that. If we let a reg sit then it just obeys the ideal gas laws as temps change. The pressure goes down when it’s cold and up when it’s hot. If the reg is perfectly sealing then the tester is just monitoring a fixed volume. If the pressure drop below the set presage in the regged volume the reg should open up again to fill it. I know you know this but this is for others. The reg works by adding the force from the regged chamber against the spring force to balance the force on the valve from the inlet pressure. Some work by using the inlet pressure to close a valve with the inlet pressure, some against it. If we say the cold is reducing the inlet pressure then that is just the same as shooting more shots off and lowering it anyway. So we know it’s not that. If we say it’s affecting the sealed off reg chamber and dropping that then the reg should open again and let more pressure in to balance it, like it would do if there was a small leak on the regged side. So it’s not that either. That’s my thoughts. I’m not convinced it’s anything to do with the reg. As a guess I think it’s just the air has less energy at lower temps. I haven’t got any non regged guns but if they do it then that rules the reg out.