My first question would be for the officials.
I agree conceptually that this has merit. Would the idea that the licence to buy a magazine or cartridge would be associated with a gun licence in the country, or are they two separate licences?
To me, it looks like there could be two ways to go about this. You could either require gun shops that are seeking to sell ammunition or cartridges to require a proof of licence, a registered gun licence, or you could simply attach a licence to purchase ammunition as a part of the condition of a registered licence.
Can the officials explain how this would play out on the ground?