The .357 question is a good one. Here in BC, perhaps not any more, but trappers and big game guides could get permits to carry a handgun for defense against dangerous animals. The "dangerous animal" being bears.

The minimum was .357 factory ammo level FPE, & they included the 10mm auto with it.
Most testing (there is a "test" performed by selected individuals) to access the skill of the licensee, however when the person is seeking license to use a .357, .38 SPL ammo is allowed, 10mm - 10S&W is allowed(not sure how that can work), .44 mag., .44 Spl. ammo is allowed and with .454 Casul, .45 Colt is allowed - by some testers. The gvt. allows this, but says one stage of the testing must be done with full powdered ammo.
I was selected by the club to test a local person, but told him he had to use full power ammo. He was 'tested" by the "other" local guy, bit of a dick, who allows the use of weak ammo.
I figure that a fellow should be able to & have to shoot what he's going to use.