My friend just got one of those, and we are planning on doing the same thing. Gonna get several different bullet/sabot types and test fire them to see what works best. So far we have both been shooting .50cal, and only use 90grns (I use 777, he uses pyrodex RS), with good results. Of course we are also gonna try some new loads in the .50cal too. Best advice is to try several different bullet/sabots and see what shoots best in your gun.