I don't have a bipod on my G22 because it's more of a field weapon for me and I don't plan to shoot far enough to need a bipod. That being said, on my long distance weapons I only use Harris bipods
http://www.harrisbipodsco.com/
I don't work for them or anything, and I know they're expensive, but I feel they're the best quality. They also sell a mount (listed about half way down, just search for "weaver") that should mount to the rail under the G22.
Hope that helps.
-Bob