I would drop to two 777 pellets. See how that works. I have better luck with the Pyrodex pellets then 777. And when I use three 50 grains, it causes my groups to fly apart. I get three shot groups under five inches with 295 or 348 grain powerbelts at 100 yards. I can reach two hundred yards without a problem and groups are ten inches. Sometimes have a flyer though. 200 yard groups are always with a solid rest. As for getting better groups. Pratice Practice Practice. Changes loads if nothing works. Change bullets if nothing works. Unjacketed sabots are legal in this state and I have seen some guys get great groups.