I apologize your gonna run the Blackjacks, RL26 may very well be your best betI've got Retumbo and H1000 but been hearing the RL26 to be the "go too" powder for this cartridge. Also V560/570 on my bench. This is just break in load starting charges I'm looking for. Guessing around 50 grains of either 4831 or RL26. I can get to pressure testing later. Just want a mild deer load for this year using the lighter bullets locally.