Benefits (How this will benefit the server and game as a whole): I mean why would I take a pistol instead of 3 more mags for my rifle? The holster would become an actual choice now instead of "webbing but much worse".
Details (Description of how you think this would work, the benefits, etc):

Implementation (Optional, if you have an idea how to implement it): Give it either storage limited to pistol magazines, or use that sweet fresh helmet strap code.