BudsGunShop.com - Action Type

Single action means the trigger only performs one action, it drops the hammer. Double action means the trigger performs two actions, it pulls the hammer back and drops the hammer. So you can have a round in the chamber hammer down and just pull the trigger instead of pulling the hammer back manually then pulling the trigger. The single action trigger will have a nice light crisp trigger pull but double action will have a long heavy trigger pull because of the pressure on the trigger from it pulling the hammer back. Hope this helps.

Ed, Josh pretty much summed it up. Have a great day!

Ed here is a graphical demonstration of SA/Double Action operation compared to Single Action and other Actions on Handguns : youtube.com/watch?v=V2be4eS_tMI