The innards are the same for all intents and purposes as airsoft. If by adding you can make it shoot faster, then the reverse is also true by taking away you can make it shoot slower. The concept revolves (pun intended) around the spring, the "stronger" it is the higher your FPS will be, a weaker spring will result in lower FPS.
There are several threads on ASC regarding how to change the FPS on Dan Wesson, and same with different branding revolvers. A search should reveal them.
Here is one: http://www.airsoftcanada.com/showthread.php?t=140922
It's like people, the outside might look different but the inside is the same.