1. If, you build a coil, for any device, that, the resistance of the coil is lower than the resistance of the Device, your device, becomes the coil and the coil becomes the resistance. In other words, the mod, would be getting hot when you fire, instead of the coil getting hot when you fire. You're creating a dead short, potential, if you use a coil, lower than .10 Ohm.
2. Battery safety. If you build a .1 Ohm coil, and fire a mech, with a battery at 4.2V, you are drawing 42 AMPs. There are many batteries that MAY claim to be 42 amp capable, but, the reality is, there are none that can achieve that in the 18650 range. 30 AMP pulse with SONY VCT 4s, that are authentic will work, at .14 Ohm, and that's really pushing the envelope of safety for the margins of errors. When you make a mistake in your calculations with this, or your battery is not quite as good as it's rating would indicate, you end up venting a battery, destroying your mod or worse.
I don't know the internals of the Hells Gate mod, so, I don't know for that question.
