Your 40 lb 7 year old son could use bear spray to effectively defend himself (and you). The same can't be said for a .357 magnum.
Take a look at the results from two studies done by Tom Smith looking at bear attacks in Alaska. The study involving pepper spray was done in 2008, the one with firearms in 2012. Spoiler: Pepper spray has a lower percentage of injuries and deaths.
Not sure I'm on board with this data. I know of at least 30 confrontations, first hand, mostly warning shots that scared the bear away. And I can't recall not ONE of my friends scaring a bear off with pepper spray.
Like I said before, the gun is a far more effective tool at scaring the animal away. A noise that cannot be duplicated with a can of pepper spray.
None of our experiences were ever asked about or published. Gun fire is a common tool where I'm from for scaring off moose, cats, and bear.