Mickey,

In many countries there are limits on the number of guns people can own. In all of these countries, the receiver is classed as the "gun" and spare barrels are considered extras but do not usually require a separate license. That, probably is the reason for multi barrel guns in a modern context.

India allows the ownership of just three guns to an individual (though target shooters are allowed to own more if they participate in ISSF competition but these could only be target guns.) There is also a ban on importing guns that are not meant for competition shooting and many Indians now import Kricos which come with replaceable stocks and barrels that allow them to be used for hunting as well as competition. In other countries where there are 6 guns per person limits and where the importing hunting rifles/shotguns is allowed, this would be a good concept, I guess. Sadly, we are sometimes forced to live with laws we hate.

Best wishes and good hunting!