Your spot on, I've spent a lot of time practicing with open sighted revolvers out to 100 yards but made a decision a long time ago that I was only going to use one in the field at 25 yards or less range. With this philosophy I could probably get away with hunting Whitetails with a 38 special.
I'm going to take a wild guess and say the dangerous game Bushfire is after will be taken at the 75 yard or less range making both the 50 & 54 caliber Pedersoli he is looking at totally up to the job with the right loads.
I've already told our guide that I won't take a shot over 50m. To me it defeats the purpose of dangerous game hunting if you're not in close.