@12358 - I concur that a longer heavier trigger can "offer" an added measure of safety, however, experience and also the testing referenced, show that it is far, far from a sure thing. If one has a ND event from overflow, startle, or loss of balance, they are often going to put a lot more than 12-14 lbs of pressure on that trigger, in a split second and the longer travel and pressure isn't going to stop that ND. There are anecdotes about long DA pulls giving guys time to change their mind about shooting, but that's not what we are talking about here. Been plenty of NDs with Beretta M9/92F, as well as Sig DA/SA pistols. Back when cops carried DA revolvers, same thing.
Some of the science behind this . . .
Regarding Sympathetic Contractions
For an average man (20-45 years, 170 lbs, 5ft 10 in), peak handgrip strength is about 125 lbs (Bemben, Massey, Bemben, Misner, & Boileau, 1996). The index finger contributes between 30 to 60% of the force to peak grip strength, depending on the position of the thumb and the width of the grip (Li, Latash, Newell, & Zatsiorsky, 1998; Radhakrishnan & Nagaravindra, 1993; Talsania & Kozin, 1998). Based on an average index finger contribution of 45%, the index finger in opposition with the thumb is capable of exerting 56 lbs of force during a maximal handgrip contraction. Because several studies indicate that a sympathetic contraction in hand muscles can reach 25% of maximum in laboratory settings (Shinohara et al 2003; Zijdewind & Kernell, 2001), a
maximal sympathetic contraction would involve an index finger force of about 14 lbs, which is sufficient to overcome most trigger pulls on handguns. This value, however, probably underestimates the actual maximum force that can be achieved by the index finger during field operations due to the modulatory effects of stress on muscle contractions
Regarding Loss of Balance
When balance is disturbed, rapid involuntary contractions are evoked that attempt to return the body to a position of equilibrium. Two features of the strategies used by the nervous system to maintain balance can evoke
involuntary contractions in hand muscles.
Regarding Startle Reaction
The reaction in the hands, which occurs less than 200 ms after the stimulus (loud sound), is for the person
to make a fist.
In summary,
scientific and clinical observations indicate that there are
powerful influences between the limbs of the human body and that these effects are large enough to evoke an involuntary muscle contraction and cause the unintentional discharge of a firearm.
Note that in the Enoka study, the force required to pull a the trigger in the position requiring the most force to overcome it (They state it was cocked) was 56.9 newtons, which converts to 12.8 lbs, and there were 9 "discharges" out of 144 events, whereas with the 22 newton (5 lb) trigger, there were 29 "discharges".
So, a lower rate of NDs (3:1) with the heavier triggers, however, still, far from perfect.
Something else - - - given the extremely high market saturation of striker fired handguns in US LE use, the rate of NDs is quite low. Now, we don't want ND's to occur at all, granted, but increasing the trigger pull does in fact make the guns harder to shoot. I know of a major (400+ LEO) agency that used to issue 96D's. Their officers had great trouble firing the guns accurately. Some of their officers were using 2 fingers to depress the triggers, the problem was so much for them. They went to a mix of 1911s and Glocks, and Voila! Everyone performed better. Furthermore, they had no issues with NDs.
So, where is the balancing act? It depends. NYPD requires a 13 lb trigger on their Glocks. They still have NDs every year, and those guns are much harder to shoot well than the standard Glock trigger.
If a 7 lb striker fired gun is so unsafe, why are there not hundreds of thousands of ND's every year by the estimated 1 million full time US LEOs, the majority of who carry striker fired guns, which lack manual safeties, and who are carrying them at least 2080 hrs each year? That's at least 2,080,000,000 man hours, not counting overtime and off duty, and how many NDs are occurring? Now, granted, a lot of NDs are not reported, but it is very standard LE policy that all NDs, on and off duty, shall be reported, upon pain of discipline, so we know that a lot of them are being reported. Further, NYPD breaks their NDs down by how they occurred.
In 2011 for example (a year chosen at random by me, a year in which they has 36,600 sworn officers) NYPD had a staggering total of 13 "unintentional" discharges: "out of Officers unintentionally discharging their firearms did so in two distinct circumstances—either purely unintentionally (13 incidents), or unintentionally during adversarial conflict (two incidents). Purely unintentional discharges usually occur while the officer is loading, unloading, or otherwise handling the firearm. Unintentional discharges during adversarial conflict occur while the officer is actively engaged in the arrest or apprehension of a subject."
http://www.nyc.gov/html/nypd/downlo...ypd_annual_firearms_discharge_report_2011.pdf
In another example, when LASO switched from the 92F to the M&P, they has more NDs. But LAPD didn't. Why? Training. LASO used to teach "on target, on trigger". That's a bad habit, no matter the trigger type.
"In 2012, there were 12 accidental discharges, none involving the M&P. In 2013, there were 18, eight of which were M&Ps. Of the 30 incidents in 2014, 22 involved M&Ps.
Assistant Sheriff Todd Rogers attributed the increase to deputies still adjusting to the lack of a safety on the new gun.
"The vast majority were people trained on the Beretta," Rogers said. "There is a correlation, no doubt about it."
http://www.latimes.com/local/california/la-me-sheriff-guns-20150614-story.html
As a comparison . .. In 2009, LAPD (10,009 sworn) had 12 NDs. 1 with a 870, 1 with a 92F, 2 with revolvers, and 8 with Glocks.
http://assets.lapdonline.org/assets/pdf/2009YearEndReportFinal.pdf
So, it's not just a hardware issue, it's also a software issue, which is why LAPD and LASO had different results after each of them transitioned from the 92F to striker fired pistols.