I faced the same problem.
I use the HKS, which is fully closed at the bottom, not the Galco, although from the looks of it, my mod should work for you too.
My modification is that I took small-bubble bubblewrap, cut several circular pieces to fit the bottom of the holder. Built-up layers until the flap pushes down on the moonclip when snapped closed (stops ammo rattle). Removed the bubble wrap and taped it into a puck using packing tape.
This has the dual effect of quieting the ammo and raising it as high as possible to grab when needed.
The same carrier does double duty for me using HKS speedloaders, so when I need to switch, I just take my bubble-pucks out.