Jerry- you're getting me mixed up with my Bro who shoots light loads in light rifles. That moose he mentioned was killed by a .50 shooting what I would consider too little powder in my book. It's just that I would use more and a .54, btw. I want a minimum of 1,800fps for a flat trajectory. Less speed will kill a moose or elk, for sure, but it's the trajectory (and accuracy) I'm after. My Canoe gun gives it's best accuracy with 90gr. 3F. I'd use that load for deer. I would not hunt moose with it as it won't give me 1,800fps, nor is it a .54. I know it doesn't take that much to kill the animal, but I won't use less. I believe in using what is most accurate and I've yet to see a .50 or .54 with a slow twist give it's BEST accuracy with such small loads. Every one I've tested with my patch combinations, gives better accuracy with more powder. In .50's it's around 100 to 110gr. and in .54's it's about 120gr. 3F or 2f- your choice. I prefer 2F for it's cleaner burning (in my guns) and lower pressure.
I would shoot a moose (if it was legal) with my .54 flint handgun (using 50gr. 3F), but I would call it into 20 yards (bow range) and plunk him through the 'lights'. It would work I am absolutely certain. It would even work using a .50 handgun with 50gr. 3F(or less), let alone a .50 rifle using the same load. I would not do that myself is all. I draw the minimum for moose at .54. bigger is better. When I say moose, I mean elk as well.
That .50 did not knock the moose down. No rifle held by a man can knock a moose down, antique or modern. The moose in question merely did not know he was shot, bled out standing where he was and collapsed. This sometimes happens. Now, a truck or car can knock a moose down if they're moving fast enough - that I've seen. I've also seen moose hit the hood, roll up a bit then land on their feet again and run off.