Does that have the Bergara barrel? I have an Accura V2 in .50 that shoots lights out. 120 grains (by volume) 75 grains (by weight) of Blackhorn 209 and a Barnes polymer tipped Splitfire saboted pill. I shimmed mine some years back and I use the Variflame Breech plug with Federal Large Magnum rifle primers. Wears a Nikon blackpowder scope. They make one helluva hole going in and an even bigger one coming out.
Mine is good to around 250 yards.