I know Bacon-Canadian and Pendred spoke about it a bit, there are also multiple people who played diverge much longer than I who claim it used to be a thing.
With the release of a bigger new map, newer factions coming, and pendred maybe finding a way to increase the server population (idk I just saw him say something about entities and trying to lower them)- I feel like it would be a good time to release attachment rackets to increase faction revenue, player interaction/rp, assist in a certain power dynamics between the illegal factions, and help the factions with activity that don’t have gun rackets.
They could also have serial numbers(for muzzles) on them, so they could be filed down, sold illegally, and police investigative rp can take place aswell- or sold legally but they must be recorded like gun store sales.
it would also help more with taking from the economy and more into the governmental budget as the attachment stamps for gun licences can hold more meaning and power such as different tiers, and how many attachment's someone can carry/transport.