Recently, I've thought that unlike WFRP or other similar fantasy game, there cannot be such things like "Weapons/Armour Shop" in the hives of the Imperium. The reason is obvious - commoners are simply not allowed to own that.
So, the question is: how the Acolytes are supposed to be getting weapons, ammo, armour and other restricted items during the scenario, which takes place on a hive? Especially, I'm interested in it if they are not allowed to show their allegiance to the =I=.
Realistic approaches are most welcome (not something like "You've spent a few hours roaming in the Underhive and purchased that big gun. Let's go...").

). But don't be too harsh on what equipment your players can buy and use (if you come up with new reasons EVERY SINGLE TIME that the guy with the meltagun cant bring his meltagun then he probably will feel like you have a particular grudge against him or something). Try instead to tailor the scenarios to what equipment your players have at hand, rather than tailoring the players equipment to suit your adventure. Because if you dont, then everything happening will just seem like you arbitrarily decide the outcome of the adventure. You'll see that the players will have a lot more fun if they have some freedom in what they can buy and use, making them really feel like it's them against their enemies, rather than being them against their gamemaster. If you know what I mean. 