I prefer flintlocks too. But for your friend, its not only caliber, its the WEATHER. My brother guided brown bear hunts for years and IF you're dealt a bad hand of weather, they sometimes averaged one out of three days the weather cooperated to leave camp and glass for hours. The rain & snow goes by the tents horizontally. If you pay 25,000 for a 10 to 16 day hunt, do the math. This is NOT an endorsement for AAA Alaskan Outfitters but if he checks their web site he could then visit with Brent Jones. Also have him click on their photo gallery of bears and scroll down to the picture of Brent H. size 13 hip boot track.
If your friend can load his flinter, prime it and seal the pan with tallow, beeswax, chapstick or whatever, lash on his best cow's knee and point it down at the drain while he showers, then when done toweling off, if it still fires, I guess he's good to go.
My son will be guiding out at Cold Bay in May. I can't remember if it was Wide Bay or Cold Bay where the wind blew the remote weather station & diesel generator off the pad into the surf.