I have leupold B&C and swarovski tds plex, I haven't looke through a bdc, why would they go with circles vs. crosshairs? that didn't make much sense to me, though for a muzzle loader I like the idea of the dropoffs associated with the bdc.....

the leupold B&C is nice, though you have to be at full magnification for it to work out to 500yds ....though then again, why wouldnt you be at full mag if you were shooting that far. so from 300-500 you need to be at full mag for it to work correctly, the swarovski works at any magnification.