Generally you should match your Nautilus Tank with variable voltage mod and actually RDA's work best with Mechs as they were traditionally used to control the output, the only thing between the battery and the vape is the self-built coil. Different builds give different resistances and vapes.
A lot of mechs have hybrid connections, meaning the attys 510 pins touches the battery directly. If the pin on the tank doesn't protrude enough, or if the pin is spring loaded, you will get a hard short. As mech's have no built-in safety, that would result in a battery vent and would be dangerous. So it is advisable that match your Nautilus Tank
with a VW mod, such as the popular Eleaf iStick series battery.