After reading many posts I have noticed somethings that really concern me. The main one is the fixation many people have with large caliber firearms. The term "stopping power" is thrown around when describing these weapons. It has become apparent to me that most people that use this term have no real idea what it means or how it relates to the undead. Hopefully I can clear this up and most likely save some lives in the process.
First I will start with "stopping power". Stopping power is simply the ability to stop your target. How this is achieved is this. A bullet enters the body damaging blood vessels and rupturing organs. Hydrostatic shock send waves of energy through the fluid of the body along the path of the wound. This further ruptures delicate organs such as the spleen and blood vessels. This in turn causes massive hemoraging. The result is rapid loss of blood pressure. Without proper blood pressure the muscles and brain do not receive adequate oxygen. This results in colapse and unconscienceness. Further blood loss causes the heart to increase pace in an attempt to compensate for the lack of blood. With the lowered oxygen available, lowered blood pressure decreasing the efficiency in which oxygen is transfered, and increased demand on the heart, cardiac arrest is likely. Larger calibers can inflict larger wounds and therefore cause these effects at a faster rate. This is stopping power.
The movies like to show people who are shot flying back from the hit, This is absolutely untrue. One of Newton's laws of physics says for every action there is an opposite and equal reaction. If people were sent flying from a firearm the person firing it would be thrown the same amount. This simply does not happen. This not stopping power.
With stopping power defined we now must look attack how it relates to the undead. All of the effects that would prove lethal to you or I have absolutely no effect on a G. They will not bleed out, they will not suffer cardiac arrest, they will not go into shock. In this case a .22 and a .50 will have the same effect (albeit the .50 will be messier which is not a great thing when you consider the spray of infected blood and matter). To have any meaningful results the brain must be the target. This brings us to accuracy.
The head is a small target and the brain smaller still. Look at someone standing 50, 75 or 100 yards away. At these distance the head appears to be 1/4 inch tall or smaller. This is your target. Add in movement, possibly poor lighting, and fear/stress and you can get an idea of how difficult scoring a head shot can be. The accuracy of your firearm is crucial. Rifles with flat trajectories are ideal. Hand guns are not accurate enough at anything but close range. This however leaves very little margin for error.
To sum things up, it doesn't matter how much damage a bullet can inflict if it doesn't land home. When choosing a firearm look for one that is accurate. Power of the round is secondary. Even a .22 can penetrate the skull if fired into the eyes or sinuses.