Explain your idea

Very basic; Just add the ability to fill a revolver and its quickloader via shift-clicking

makes loading it quicker and more convenient; Obviously a QoL thing

To clarify: I mean for loading cartridges into their slots

It's intentional behaviour to prevent loading the revolver via shift-click - that makes it take time to load, making the capacity upgrade and quickloaders have a use with distinct behaviours. It also gives a bit of a downside to the revolver compared to bows and the railgun. It's up to you to decide which tradeoffs are better.

Yep, what Spen said!