I post here infrequently so I hope all of you will indulge my thoughts on the subject. The weapon-mounted light (WML) has to be one of the most, if not the most, misunderstood/maligned pieces of equipment. Having spent a good portion of my entire adult life preparing to fight in a low-light environment I am convinced of the WML's utility. When employed properly it is an awesome tool. As the debate seems to hinge around the employment of WMLs on handguns, I will focus on their use with a handgun though much of the information pertains to WMLs on shoulder weapons as well. Let me begin by addressing some of the more common negative comments regarding WMLs:
1. It violates Rule #3: Never allow your muzzle to cover anything you are not willing to destroy. I would submit that if I have accounted for all of my loved ones (which is the first thing I do when the proverbial "something goes bump in the night") then I am willing to destroy anyone whom I find uninvited in my home. If it turns out to be someone who belongs there, then I am no longer willing to destroy them and the light and muzzle come off target. Let me be clear, pointing a firearm at someone is a serious act and is one not to be taken lightly. That said, it is done perhaps hundreds, if not thousands, of times a day without incident. There is also an enormous amount of ground to cover between being willing to shoot someone and actually deciding to do so. If you choose to put yourself a little further behind on the power curve by waiting to determine if the individual has the ability and intent to harm you before you point your weapon at them, who am I to disagree? But let's be clear, you have accepted a not-so-insiginifcant amount of risk to yourself, and by extension any loved ones in the house, in order to be able to provide an extra margin of safety to someone who had no business being there in the first place. Another related and oft-cited criticism is the potential use of a WML light for mundane tasks like looking for your keys if you drop them. If you would consider using your WML as a general-purpose flashlight, you probably have no business owning a firearm.
#2. It makes you a target. Yes it does...when employed improperly. If I put an individual in a completely darkened room and told them to shoot at the light when it came on, there would be a problem. I would submit that the individual(s) in your home are probably pre-occupied doing something else and are not waiting to ambush you. If they are, you have probably already made a tactical error which has no bearing on your choice of illumination tool. Where a light does make you a target is when you are attempting to clear spaces that exceed the ability of your light (i.e. warehouses, hangars, backyards).
#3. Just use the light-switch. While this is a functional solution, it is probably not the best tactical solution. I can not think of a better way of announcing my position and progression through a building(other than by beating on a pot) than by turning the lights on as I enter a room. But that is not the only problem. You provide the bad guy an advantage if he is in an adjacent room. Stand in a well-lit area (where you will be) and look into a darkened area (where the bad-guy will be). How much can you see? Now put your bad-guy hat on for a moment and stand in the darkened area and look into the well-lit area. Who has the advantage? But what if he is in the same room? A ceiling fixture distributes light throughout the room. Both the bad guy and I can make equal use of the light. A light, either hand-held or weapon-mounted, allows me to project light only into those areas where I want it to go. He may be able to gain some residual benefit from my use of the light, but I control it. If I determine that residual benefit is too great, I can turn the light off.
WMLs have two distinct advantages over hand-held lights. First, they are more efficient to fight with. This is not to say that one can not fight effectively with a hand-held light. You most certainly can. However, all to often when discussing employing a light , the discussion stops at the first shot. The whole reason the firearm is present is because we acknowledged early on the potential for a fight. When we talk about a gunfight most of us understand that the potential exists for it to go beyond that first shot. To that end we practice a variety of skills ("double-taps," failure drills, malfunction clearance, reloads, multiple targets, etc.) If the gunfight occurs in the dark, we have to be able to perfom those same skills. There are techiques for performing all of them with a hand-held light but all of them are slower than if the light were weapon-mounted. A major problem many people have is aligning the light with target without compromising the sight picture/alignment. Typically, after the first or second shot, most people have their hands come apart, effecting their accurancy and speed. Conversely, my shot to shot times are typically faster due to the increased mass the WML provides with no reduction in accuracy.
Not convinced? Try these three tests; once using your hand-held technique of choice and once gripping the weapon normally (as you would with a WML):
#1: 6 rounds from the ready
#2: 2 rounds, reload, 2 rounds
#3: 1 round, tap-rack, 1 round
Compare your times and accuracy for each.
Second, WMLs do not require multiple skill sets. All of the aforementioned skills need to be practiced. The reality of using a hand-held light is that you usually need to employ one of several hand-held techniques depending on the situation. You may prefer the Harries Position until you have to pie a corner to your left, which allows your muzzle to clear the wall while your light may still be behind it. Leaning further out to clear the wall exposes more of your body necessitating a change to a "left-side" technique like the Rogers.
For a well-trained person using a hand-held light that generally means three skill sets: no light at all, a "right-side" technique and a "left-side" technique. (Though to be fair, there is a fair degree of redundancy between the two hand-held techniques making it really more like 2 1/2 skill sets.) A WML requires little, if any, change to your manual of arms. I do not know about you, but it seems like I never have enough time to train.
Having said all that, WML's do have their drawbacks. First, they are expensive. Second, they require training to use properly. Third, they require you to expose slightly more of you body when dealing with a corner. Finally, they can be heavy depending on the application.
In the end, the equipment an individual chooses to defend himself/herself and his or her loved ones is a personal decision. However, such a decision should be an informed one.