I have a light weight 20 ga. Ithaca Flues with damascus barrels. So far, all I've been shooting is 2 dram of 3F black behind 3/4 oz. of shot. I would like to use the same load but in smokeless. What PSI is considered "light" for a 20 ga? What powders give those kind of pressures with 3/4 oz of shot?
Thanks,

Jack K