looks to me from looking at some load data using 200 grain bullets makes it no better than a 444 marlin but then those hornady 200 grainers are pointed bullets right? so they probably have a ton better BC then your typical 200 grain pistol bullet. but then with heaving a 300 grainer out there it looks to be getting 45-70 rifle performance from a pistol. I think if i werent able to get those light weight pointed bullets like the hornady factory ammo Id probably go heavy unitll they were available for reloading.

asfar as light target ammo goes, i not real sure of all the details but my friend with the BFR in 450 marlin has a light load for the 450 marlin he uses in his bfr that pushes a 350 grain lead cast around 800 fps. I dont know the powder he uses but he uses backing rod from the hardware store as a filler to keep the powder against the primer. if you like I can talk to him and get the details if you are interested in knowing what he does.