No need to prime your encore. I would think that if you were using 3 pellets of 777 that it was a 150 gr. equivalent. The new powder of choice seems to be Black Horn 209. This powder along with the 250 gr Shockwave and a Harvester 50/45 cal. short black sabot would be a great combination. I would probably start some where around 90 gr. of the BH209 and work my way up. Work with the different powder charges untill you find the sweet spot. Hope this helps. You may also want to try the Hornady XTP .430 / 300gr bulletwith a Harvester Green Crushed rib sabot since you said that you were going to keep your shots close. I have heard that this is also a good combination. Good luck.