I've killed them out to 125 yards with my .54 and a round ball, with my .45 I limit myself to about 75 yards...So, I'm guessing stay inside 100 and you should be ok...90grs of FFF Goex is a pretty stiff load in a .50, especially with that stock design, a conical will kick the heck out of you and they are not needed for deer...I'd drop down to 75-80 grains on that charge...I used 75 with my .45 for years and use 80 on my .54...With round balls you will find that the faster you start them, the faster they slow down so there isn't really an advantage to trying to push them too fast...The key to accurate round ball shooting is the patch fit and lube...I used to shoot in competition and if you couldn't keep all 3 shots inside 1 1/4 inches at 50 yards then you wouldn't finish in the money...That lead round ball is much deadlier than most know, they come out with all sorts of formulas to prove it wrong, well I've hunted with them since the mid-70s and I can promise you, you don't want me shooting at you at 150 yards with one.....