Try Pittsburgh Paints Dover Gray. It looks dark on the card but goes on a medium gray tone. I think it's a very nice gray, and I sampled several before I chose it for the exterior of my house.

Here is a link that might be useful:

Thank you! I will check out this color. Thanks for sharing the fruits of your hard work weeding out the grays!

Just bumping this one. Looking for good options for a medium gray myself. Tried BM Thunder but once I sawa a larger sample am worried that might be too light. Any other suggestions?

We really like this grey -- may be too light for you. It was the color of the primed new wood, and we had it color matched and painted the whole house. BM C2 Monday Morning.