NiB is much better for triggers than NP3. Teflon will not stand up to the high pressures generated on sear edges. NiB is upwards of 70Rc hardness. That said, DLC is even lower friction, so I've been curious to experiment - maybe this is the project.
Not sure about charging handles, I know how to make good triggers, and it seems everyone and his brother is making charging handles because it does not take much skill. What is your definition of 'badass' when it comes to charging handles? Is there something that other options do not offer>