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Got this in a Force Science Institute newsletter today and though it may be of interest to those with gun-mounted flashlights:

http://www.forcescience.org.

Force Science warning: Gun-mounted flashlight device susceptible to fatal errors under high stress

The Force Science Institute strongly cautions LEOs to avoid a switching device that attaches to a popular gun-mounted flashlight and creates risk of an unintended firearm discharge during high-stress confrontations because of its design.

At least twice in recent months the device has been associated with shootings in which officers reportedly said they thought they were turning on the flashlight attached to their semiautomatic pistol when in fact they were pulling the weapon's trigger. One civilian was killed, the other seriously wounded in the consequent firings. Both were unarmed when shot.

Without commenting on the specifics of either case, Dr. Bill Lewinski, FSI's executive director, recently explained to Force Science News how a fateful interaction between human-performance dynamics and ill-conceived product configuration can cause such tragic confusion.

"In normal, nonstressful conditions or even under mild stress, the mechanism in question is likely to work as intended," Lewinski says. "But under high stress, when an officer's hand movements tend to be automatic and rapid, it can be a much different story.

"Because the problem is not likely to be corrected even with considerable training, the Institute recommends that for the safety of officers and subjects alike this particular switching device be avoided."

The mechanism in question is the DG grip switch assembly for the X-series of weapon lights produced by SureFire LLC, headquartered in Fountain Valley, CA. This optional switching mechanism fits on the tail cap of a SureFire X200, X300, or X400 flashlight which itself locks onto rails under a pistol's frame in front of the trigger guard.

The thin, flat, narrow housing for the grip-switch controls follows the outside contour of the trigger guard and then bends down a bit against the front strap of the grip. There, a small finger pad allows for on-off manipulation of the light. [CLICK HERE to see a photo of the switching mechanism and its relationship to a pistol.]

The benefit of this mechanism, according to SureFire's website, is that the officer behind the gun can "activate the light with finger pressure without needing to move a finger from the grip." The finger pad can simply be pressed with the "top grip finger, leaving the index finger free to operate the handgun trigger."

The problem with this, Lewinski explains, has nothing to do with the functioning of the flashlight itself. "SureFire flashlights are popular with law enforcement because they are powerful and effective," he says. Indeed, he recently bought one of the company's hand-held models for his personal use because of its exceptional brilliance and reliability.

"But the grip-switch operational option, while convenient, carries significant risk related to possible unintended discharges," he says.

One possibility, Lewinski asserts, is that under stress, when the exertion of physical pressure tends to become intensified, an officer pressing his middle finger against the flashlight switch pad will produce a sympathetic reaction in the index finger. If that finger happens to be inside the trigger guard and on the pistol's trigger, the reaction may be forceful enough to cause an unintentional discharge.

Ideally, of course, the index finger would be outside the guard and on the frame until a conscious decision to shoot has been made. But research studies have convincingly shown that, despite training to the contrary, officers in high-stress situations tend to move the finger onto the trigger, often without even being aware they have done so. [See FSN Transmission #3, 10/15/04, "Can You Really Prevent Unintentional Discharges?" Click here to read it.]

Another risk Lewinski foresees is the psychological stress phenomenon called "slips-and-capture" error. This would involve confusing the flashlight grip-switch pad with the pistol trigger, which are mere centimeters apart and require a similar action to activate.

Lewinski explains: "Slips-and-capture errors occur when a person is performing unconscious, automatic-type behavior under a high level of stress, time pressure, and sense of urgency. An intended behavior slips off the rails, so to speak, and is superseded or 'captured' by a more powerful, more frequently practiced automatic behavior. The error occurs so quickly that the person doesn't have time to catch it and correct it.

"If the action was happening in slow motion and the person was able to think about it logically, it wouldn't make sense and he'd correct it. But under stress and urgency, the action happens so fast and so unconsciously that it's impossible to self-assess, analyze, and readjust it."

In the civilian world, this phenomenon often makes the news when drivers confuse the accelerator with the brake and cause a car crash. In law enforcement, an example would be mistakenly drawing your sidearm when intending to draw your Taser, which has been documented in multiple instances.

"When you think you're doing one thing but are actually doing another, the result often is directly opposite of what you intended," Lewinski says. [See FSN Transmission #154, sent 7/19/10, which discussed slips-and-capture in context of the high-profile BART shooting in California. Click here to read it.]

To date, Lewinski has been involved as an expert witness in 4 cases in which slips-and-capture played a role. "It is a well-researched, real-world phenomenon," he says, "and the SureFire grip switch appears to be dangerously vulnerable to it."

Even extensive training may not be sufficient to overcome the attachment's potential flaws. "No amount of training can override certain well-defined human performance factors," Lewinski says. "It makes more sense to accommodate behavioral dynamics in the way tools are designed for use in high-stress situations."

In the case of the grip switch, Lewinski recommends relying instead on the on-off mechanism that is built into the flashlight itself and can be activated when needed with the non-dominant hand.

Force Science News made repeated efforts to reach someone at SureFire to comment on the switch issue. The firm's public relation's manager replied by email to a voice-mail message that he was "bouncing around the country" and could "not promise phone time" to talk about the grip assembly. At his request, questions were submitted by FSN via email, but at this writing, nearly a week later, no response has been received. Phone messages directed to the company's chief engineer were not returned.

The 2 known unintentional shootings involving the grip mechanism occurred in Plano (TX) and New York City.

In Plano, an undercover sergeant fired his .40-cal. pistol during a drug sting last October in a fast-food parking lot. In a written statement, he said, "I never intended to have my finger on the trigger. I was attempting to squeeze the light mechanism [on a SureFire X300] when my weapon fired and the suspect fell to the ground," mortally wounded.

The New York shooting occurred last January during a drug raid in an apartment building. The first detective through the door of the targeted unit fired his 9mm semi-auto and struck the 76-year-old father of the suspect being hunted, wounding him in the abdomen. A police official was quoted as saying that the gun discharged as the detective "tried to adjust a [SureFire X300] flashlight attached to it."

At that time, SureFire's vice president of marketing told reporters, "Our product has been proven safe. Used in a safe manner, it doesn't lead to accidents. It prevents misidentification and saves police lives."

Lawsuits have been filed in both shootings.
 

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Having used mounted lights, I can say that I am not a fan. I agree with the above mentioned problems as that is the same reason why we don't use them.
 

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hyrax said:
Having used mounted lights, I can say that I am not a fan. I agree with the above mentioned problems as that is the same reason why we don't use them.
Have you noticed the same phenomenon associated with the use of lasers also?
 

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I, personally, have not used them on my carry firearms. I have seen them come out of adjustment a few times in hard training use with other agencies. Some were severe enough to warrant their removal to continue the class. I'm sure there are many that have performed flawlessly. Some love them, but I'm not a fan.

If I want bling for my firearm, I'll get it engraved or something. Maybe with someone else's fingerprints.
 

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I see this more of the officers having a finger on the trigger rather than the design of the switch. If there is no finger on the trigger while activating the switch in question than there should be no way to squeeze the trigger.
 

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usarmysldr said:
I see this more of the officers having a finger on the trigger rather than the design of the switch. If there is no finger on the trigger while activating the switch in question than there should be no way to squeeze the trigger.
Indeed.

My "under the bed" Beretta has a Streamlight TLR-2 on it, that has a little rotating lever thingy you flip with your trigger finger (outside and ahead of the trigger guard) making it pretty much impossible to pull the trigger while activating the flashlight.

But as they say, make something idiot proof and "they'll" make a better idiot. Training and paying attention is the first most important thing here, THEN a design that doesn't assist bad habits.
 
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