How to convert Stack into bulk:
> Eject bulk of crossbow bolts.
> Load them into the crossbow.
> Drag them out agian. They are a bulk again.
--------------------------------------------------------------------------------
How to reload it:
> Load a quiver or some other bolts into the crossbow.
> Have a bulk of bolts into your inventory while crossbow is already loaded
> Scroll or press "f" you can now reload with the bulk, which acts like a quiver/snap/speedloader. And only takes up 1 inventory space.