* I stole this from another site since it is better than I can explain it
Revolvers come in many flavors, many shapes and sizes, and many different configurations. The two main platforms are the single action and the double action. Which one is best for you is ultimately a matter of preference. Which is most comfortable in your hand, and more importantly the revolver you can shoot most accurately, is the one you should choose.
Single and Double Action Differences
Single actions derive their name from the fact that they can only be fired by cocking the hammer and squeezing the trigger one shot at a time, whereas the double action can be fired in the same manner as the single action or simply by squeezing the trigger to fire – hence “double action.”
All modern day single-action revolvers are based, however loosely, on the Colt Single Action Army (SAA). So timeless was the design that it is still in wide use today. There are a number of manufacturers of single-action revolvers, including Ruger, Freedom Arms, Magnum Research, Uberti and Colt.
Double-action revolvers are available from Smith & Wesson, Colt, Ruger and Taurus on the new and used markets. Colt’s excellent Anaconda is no longer in production, but it can be found used and makes for an excellent choice for hunting or as a back-up weapon.
Both types of revolvers can be chambered in calibers adequate for big-game hunting and protective back-up duty, but they handle recoil differently. Double actions tend to transfer all of their recoil straight back into the web of your hand, while single actions have a propensity to exhibit barrel rise and are designed to roll upward (particularly in the case of single actions equipped with “plow handle”-type grips).
** As the name implies, single shot refers to any firearm–which may be a pistol, rifle or shotgun–that has no magazine and holds a maximum of one cartridge at any given time
A semi–automatic pistol is a type of pistol that issemiautomatic, meaning it uses the energy of the fired cartridge to cycle the action of the firearm and advance the next available cartridge into position for firing. … A semi–automatic pistol harnesses the energy of one shot to reload the chamber for the next.