My neighbor gave me an expired can of bear spray and I drove with it up to Glacier for the start of my CDT hike. Unfortunately it sat too long in the hot car, and maybe because it was an old can, it leaked. Liquid pepper spray is very annoying, too. That was about five years ago, and I still sneeze when I open that pack. You might want to mention that caution to your brother.
I bought a new can at Glacier at a $10 penalty, and used the leaky one as practice. I would recommend anyone who's serious about hiking in grizzly country do that. A friend of mine just went and bought two and shot one off for practice.
I did not get any blow back on a calm day, and I'm sure I got more than 20' before dispersal. The one I used was only a couple years out of date. I would carry a can that's had a test spray out of it.
As I hiked out of grizzly country south of Yellowstone, I gave mine to one of the cowboy guides at Brooks Lake Lodge. He appreciated it very much. He said all the guides used it as their first line of defense with their horses and customers (in that order).