My thoughts on this... considering there is no "cowboy culture" in Europe and nobody is allowed to carry openly unless you are a LEO in full uniform.
Having to think "what to do, how to protect myself" when all goes haywire, my thoughts immediately go back to the trapper/cowboy who, way back in the 1870's, required a "do-all" cartridge.
One cartridge for his lever-action rifle, and for his revolver.
In those days of "smokey" black powder, it was the 38-40 or the 44-40. These days, you'd translate those black powder cartridges as the .357Mag and .44Mag. OK, why ? And what do I gain ?
Firsto of all, a revolver and a lever/bolt/pump action rifle chambered for the same cartridge mean you have only half the logistics to worry about,
much like having many vehicles but all running of the same fuel and the same oil (and maybe even the same tire size).
In other words, only one kind of primer, powder, dies and quite possibly even a single bullet design may do.
Secondly, it means that "when out and about" you should never "run out of ammo" for one particular weapon.
Third, both cartidges have the softer, "Special" equivalent caliber which may be reloaded with very soft charges in order to allow for training, plinking (very much the same)
and sub-sonic shooting (when you nees a "poof" not a "bang" as in poaching or getting even).
Fourth, cylindrical cartridges are the simplest to resize and recycle umpteen times, over and over - unlike bottleneck cartridges which may bend, kink and chink beyond hope... and which require jacketed bullets else the barerel leads up.
Last... (and this holds true especially for .44 cartidges) you can concoct your own home made shotshells even for a rifled bore, keeping in mind they're only good a few feet away from the muzzle...
...but they still pack a bang and work when you need to spray the area!
In other words... I wouldn't waste my time with a fancy "assault rifle" stile carbine, nor with an auto that holds 15 rounds in a clip, when I can't reload either... or it's such a hassle that it is eventually not even worth it.
(PS The revolver cartridges also allow you to experiment some veeery interesting bullet designs... )