Big Game Powder in Gas Gun

[Burt Gummer]

First time poster and hand loader. I have an 18” barrel gas gun in you guessed it, 6arc and was curious if this would be a good fit for the cartridge seeing it’s very close to LVR. I picked up a pound to try but not sure where to start with charge weight. If nothing else I’m going to need some powder to fire form some new brass!  . Does anyone have any experience using this in their gun and if so what sort of data would you feel comfortable sharing?

Thank you for reading