How much 777, and what choke are you using? There are millions of combinations you can come up with, but in my White Thunder (Tominator) 90 gr 777 FFG, BP Turkey Ranger shotcup, filled with #5 Magnum lead shot (1-3/4 oz approx), 2 styrofoam over-shot wads will turn out ol' Tommys lights out at 40 yards without a problem. I have two that were taken at further ranges, but unless you KNOW what your load will do I wouldn't suggest it.
My Knight TK200 has a jug choke and uses the 3-1/2" shotcup, that might be too much cup for your Encore. Those shotcups will hold 2-1/4+ oz of shot, might want to get something that will hold about 1-3/4 oz to 2 oz of shot. Have you tried any shorter shotcups? Bigger is not always better when trying to work up a good shooting load for turkeys.
I'll take my White Thunder shooting 1-3/4 oz of shot over the Knight TK2000 shooting 2-1/4 oz every time.