Tuesday, July 19, 2011

Safety Mechanisms

In the next series of blog posts, we will look into a very important topic: firearms safety mechanisms. So what is a firearms safety mechanism and why do we need them? Well, a firearm is a weapon and we do not wish to use a firearm unless absolutely necessary, for obvious reasons. Therefore, there must be some mechanism or mechanisms that protect a firearm from accidental discharge, for example, if it were to be accidentally dropped, or if the firearm was hit by a rock or a ball or some such flying object.

The first way to do this is to carry a firearm in such a manner that it is loaded, but the user must perform an additional action before the firearm can be discharged. For example, with revolvers, people generally carry them with all but one of the chambers loaded. The lone chamber that is left unloaded is then rotated so that it is directly under the hammer and the revolver is also left uncocked. So, if the revolver were a six-shooter, the user loads five out of six chambers in the cylinder and then rotates the cylinder so that the empty chamber is the one that the revolver's hammer is directly pointing at. Therefore, if the hammer is accidentally struck, it only falls on an empty chamber. To deliberately discharge the firearm, the user needs to pull the hammer back fully with his thumb (assuming a single action revolver), which cocks the hammer and also rotates the cylinder so that the hammer will now fall on a loaded chamber. For a double action revolver, the user pulls back the trigger fully. Since it is acting in double action mode, the revolver trigger pull is much heavier and the trigger pull simultaneously cocks the hammer, rotates the cylinder to the next chamber and then releases the hammer. While this technique is actually a "policy", not a "mechanism", on many revolvers (especially older ones), this is often the only "safety mechanism" that users have.

Similarly, for modern pistols, shotguns and semi-automatic and automatic rifles, users may simply fill the magazine with cartridges and load it in, but carry the firearm without a cartridge in the firing chamber. To discharge the firearm, the user needs to hold the firearm with one hand and use the other hand to pull back on the slide (or lever in case of some shotguns or rifles) to cock the weapon and also load the first cartridge from the magazine into the firing chamber. Then the user can pull the trigger to discharge the firearm. Therefore, it takes a conscious pair of actions before the firearm is made ready to fire and it cannot be discharged unintentionally, if say, it were accidentally dropped on the hammer. This method is sometimes called the "Israeli Carry" method in the US and Canada. The origin of this term is because in the early days of the IDF (Israeli Defense Force) history, they had severe budget constraints and were forced to acquire large numbers of antiquated firearms with questionable mechanical safety mechanisms. Therefore, the early IDF personnel were taught to carry with the chamber empty and hammer down.

Of course, quite a few people like to carry their firearms loaded and cocked, with one cartridge already in the chamber (called the "+1 carry method" i.e. magazine fully loaded + 1 extra loaded in the chamber), because they do not like the idea of spending extra time to prepare the weapon for firing, which may cost one's life.  Also, there may be a chance that the user may drop the weapon after they have begun firing. Obviously, there needs to be safety mechanisms to protect against these situations as well. These are the mechanical safety mechanisms we will study in the next few posts.

Safeties can be divided into two major types:

  1. External or manual safety: These typically consist of mechanisms which explicitly require the user to switch them on or off separately. For example, there may be a safety lever or button that needs to be pushed to turn the safety mechanism off.
  2. Internal or automatic safety: These are typically turned on or off as part of another action. For instance, many modern firearms have a hammer block that prevents the hammer from striking the firing pin. Only when the trigger is pulled is the hammer block moved out of the way of the hammer's path. Therefore, the act of pulling the trigger deactivates the internal safety and the hammer will not strike the firing pin if the firearm is accidentally dropped.
Many modern firearms come with a mixture of both types of safeties. We will look into various safety mechanisms in the next few posts.

As might be noted, the argument about carrying a firearm with the chamber loaded or not is an ongoing one. Some argue that it takes too long to load a cartridge into the chamber, while others say it doesn't take that much extra time. Others argue that in a stressful situation, one may forget to load the weapon. Also the user may not have both hands free to do this. These days, with access to better firearms, the Israelis have even stopped teaching the so-called "Israeli carry" method for the last 20 years or so. The following pair of videos shows both techniques:

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