Your son has an 870, and that's good, but if it is not on his person it's not good. Jeff Cooper once wrote that a pistol is used to fight your way to the closest shotgun. That tells me that, in case of man or beast, carrying a big handgun on you is much better than a shotgun in a truck. Bears may, at times, attack very fast. But, there have also been many incidences where a handgun has warded off what may have been a fatal attack.

May God bless America and those who defend her.