Make a "User.cfg" file in your game directory, and paste in: RenderDevice.PresentAsync 0
That should allow 3rd party screen recorders to get detected, including Action!.
Edit: If you want to see your actual FPS while recording and without using another software, paste: PerfOverlay.DrawFPS 1
Edit 2: If you're not sure about creating the file yourself, here's a download to the one I made (both ingame FPS counter and 3rd party recorder): https://www.mediafire.com/?808820ud56lm7vr
Edit 3: This technique may get you banned and treated like a hacker! Your loadouts will get locked and reset to default, prices will go up 1000%, and you will get blacklisted from the forum and ranked servers!