I have the same EXACT gun and I have tried a few different loads and am in LOVE with the one I worked on this year. I put a Nikon ProStaff 3x9 scope on it and it is dead accurate.
I am using 2 50gr. Pyrodex Pellets and a 350gr. FPB bullet. Mine is amazingly accurate. I feel confident up to 150 yards.......
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BEAR Charge Bow
RAM CAT Broadheads
Remington 870-20 Gauge
Hornady 20 GA Slugs
CVA Optima Pro - 50 Cal.
Hornaday 350 GR. FPB