Would Mercury Quicksilver grease work in my wheel bearings?

If you've never repacked the bearings, I'd suggest to pull the hubs,inspect the bearings and brakes, repack with a high-temp bearing grease.

You never know, the last guy may have used some Mercury Quicksilver grease.

BTW, there is a way to unload and load another cartridge into a gun. If you still have a Mercury, you may wish to just buy another gun. They aren't that expensive.