Love'n the back and forth with Looney, Leedo and Reaper... Hoooah!
I'm still gonna go with the theory that the Mallers are picking up brass for reloading. It doesn't have to be a station. They simply have to save it until they get where they need to get.
Looney has missed a lot of the convo's about what the Mallers have been doing since Scratch saved them and how they covered so much territory..
Remember, they've raided every damn thing from LAX to the Arena. Multiple police stations, Burt's shop, the Guard Armory and Lord knows what else. Durai telling them to find a place that has the powder They're bound to have people that know how to reload. Having a few gunsmiths among the regulars or the slaves seems very plausible. Hell, they may even have a ton of books from the prison library that any mechanical minded person can read and do.
I'm pretty sure Datu could learn to reload with the right equipment and a manual.