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New Study: Grip Strength and Shooting Performance

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A new study led by Ph.D. student Andrew Brown1 examined the effects of grip strength and gender on shooting performance.2

Brown and fellow researchers sought to verify independent studies showing that grip strength was directly related to a person’s ability to manage aim, recoil, and trigger pull. These skills are widely recognized as some of the key components of superior shooting performance.

This latest study was designed to replicate previous research relative to grip strength and to identify what range of strength might be required to achieve shooting test standards. The resulting data was used to examine the relationship between grip strength, gender, and shooting scores.

Shaking Hands

According to the researchers, a standard-issue 9 mm pistol might have between 4lbs-6lbs of trigger pull weight. A double-action-only pistol might be closer to 9lbs-12lbs. Still, trigger pull weight can depend on the type of gun, the hammer mechanism (e.g., single-action vs. double action), and whether mechanical adjustments have been made. As a rule of thumb, the amount of pressure required to pull a trigger and fire a round (“trigger pull weight”) is roughly equivalent to a firm handshake.

Researchers explained the influence of trigger pull weight: “Trigger pull weight appears to impact shooting performance as triggers that are too heavy [for the individual shooter] seem to activate additional muscles in the hand.” They continued: “If the trigger pull of a firearm exceeds the force of a handshake, isolation of the index finger becomes difficult, causing the hand to engage in the use of additional muscles to complete the task of pulling the trigger. The overcompensation of unnecessary muscles, in turn, negatively affects shooting performance through involuntary hand movements.”

The questions remained, how much strength is needed to avoid these grip-related issues and pass a standard police pistol course, and will an officer’s gender predict negative shooting performance related to grip strength?

The Study

Researchers had 118 active police officers, ranging in age from 22-62, conduct a standardized police pistol qualification using a double-action-only pistol with a trigger pull weight of between 8lbs-12lbs.

Before attempting to qualify, the participants completed a demographic questionnaire to document their age, rank, gender, and years of police service. Researchers then measured and recorded the participants’ dominant hand maximum grip strength.

After their grip strength was measured, participants performed the police pistol qualification with stationary targets between 10 and 82 feet. The results of the tests were analyzed and compared to the grip strength measurements and officer demographics.

The Results

Male officers in this study had, on average, higher qualification scores than the female officers. 21.9 % of the female officers in this study failed the qualification compared to 8.1% of the male officers. Researchers theorized that insufficient grip strength would negatively impact shooting performance, and that female officers would, on average, have lower grip strength than male officers. Both theories were supported by the research results.

First, researchers determined that grip strength in the range of 80lbs and 125lbs was needed to score approximately 85% and 90% on the pistol qualification test. The average grip strength for the female officers in the study was 77.5lbs, while the average for the men was 121.5lbs.

78% of the females and 92% of the males passed the qualification test (22% and 8% failed respectively). Researchers observed that, for every pound below the average grip strength required to score between 85% and 90%, the odds of an officer failing the pistol qualification increased by 2%.

Discussion

Shooting performance is influenced by a variety of factors, and it appears that grip strength is certainly one of them. Andrew Brown provided the following observations: “In our study, higher rates of failure appeared to be correlated with lower grip strength.” Brown continued: “Agencies should consider minimum grip requirements based on the issued duty pistol trigger weight. Although grip strength issues might disproportionately impact female officers, strength training may help to mitigate grip-related deficiencies regardless of the officer’s gender.”

A recent article in Officer.com reported that NYPD is moving toward lighter trigger pull weights for their recruits. This move is consistent with Brown’s recommendation that agencies “examine the adoption of pistols with lower trigger pull weights to mitigate grip strength related shooting issues.”

Dr. Bill Lewinski, executive director of the Force Science Institute, supports Brown’s recommendations and was encouraged by the NYPD’s move to a lighter trigger pull weight: “We often hear that higher trigger pull weights can provide increased decision-making time for officers. The research does not support that position.” Dr. Lewinski explained: “Even the heavier triggers can have a travel time as quick as 6/100 to 8/100 of a second. If the decision to pull the trigger has already been made, the travel time of the trigger isn’t going to result in sufficient time to change your mind and stop that action.”

Mitigating Unintended Discharges

Dr. Lewinski addressed another concern that often accompanies lower trigger pull weights: “Agencies are always looking for ways to reduce the number of unintentional discharges, and trigger pull weights should always be a part of that discussion.”

Lewinski cautioned, “Researchers have observed officers unintentionally and non-consciously touch the trigger of their firearm while they were engaged in vigorous physical movements during a simulated high-threat robbery scenario. About 6% of those officers unintentionally applied sufficient pressure to pull a 12 lbs. trigger weight. More importantly, nearly 20% unintentionally applied enough pressure to fire a gun with a 5 lbs. trigger pull weight.”3

Dr. Lewinski reiterated what remains the most important consideration for avoiding unintended discharges, “In our research, we saw that around 31% of the unintended discharges involved striker-fired weapons. Of those, well over half of the unintended discharges were the result of intentionally pulling the trigger before clearing the chamber during disassembly [i.e., field stripping the weapon]. To mitigate unintentional trigger pulls and subsequent discharges, including cases that involve muscle co-activation, startle response, or routine weapon handling, keeping the finger outside of the trigger well is a critical safety protocol regardless of the trigger pull weight.”      

The complete report, titled “Examining the impact of grip strength and officer gender on shooting performance” can can be accessed by clicking the button below.

Please note the above link will direct you to a third-party website that charges an access fee to view the full research article. The Force Science Institute itself is not charging for this paper and does not receive payment, in part or in full, for copies of the publication.


Additional Reading

Related Force Science News: Can You Really Prevent Unintentional Discharges?

Related Force Science Research: Toward a Taxonomy of the Unintentional Discharge of Firearms in Law Enforcement.

  1. Andrew Brown is a Ph.D. student in Psychology at Carleton University, Ottawa, Ontario, Canada, He has a B.A. and M.A. in Psychology. []
  2. Andrew Brown was joined by fellow researchers and Ph.D. candidates Simon Baldwin and Brittany Blaskovits, as well as Dr. Craig Bennell, Ph.D. in Psychology. []
  3. See Heim, C., Schmidtbleicher, D., & Niebergall, E. (2006a). The risk of involuntary firearms discharge. Human Factors, 48(3), 413-421. doi: 10.1518/001872006778606813 []
12 Responses
  1. Al Sowers

    One thing that comes to mind in this study; does the gun fit the hand? A small hand on a pistol with a large grip could mimic poor grip strength and support the qualification failures. It would be interesting to follow this study up with different grip sizes for those who struggled.

    1. Todd Nobbe

      I agree with Al’s question. I have actually found that matching a smaller grip with a smaller proportionately hand has increased accuracy. This test combined with grip strength may help provide a more detailed analysis.

  2. This is not new information, nor do you need a PHD to realize that women do not possess the same grip strength as men-on average.
    Keeping your finger off of the trigger until you are ready to fire has always been a 101 protocol.
    By lowering the trigger weight I’m sure we will see an increase in negligent discharges since many of these officer violate the 101 protocol.
    Trigger squeeze is the #1 issue with shooters. With proper training, even female shooters, can be trained to manipulate the trigger effectively.
    The study went out to 25 yards! Even good shooters ha e trouble holding consistent groups at those distances! Keep it within 7-10 yards and I think performance will improve.

  3. DeEtta Jacobs

    I would like to see a follow up study with participants who are already accomplished shooters. If a shooter has already demonstrated the skill needed to successfully pass the firearms course then it further eliminates other factors from the hypothesis surrounding grip strength. If all of the shooters are of equal skill in the beginning and the trigger pull weight is incrementally increased, accuracy based on trigger pull would be better correlated. In addition, the same method could be used with handle size as mentioned in the response from Mr. Sowers.
    Just additional points to ponder.

  4. It all breaks down to training. Training does not make perfect, perfect training makes perfect. Many departments do firearms training once a year, maybe twice, due to the lack of personnel and budget issues. Police officers will respond to situations, according to the way they were trained. As for reducing the amount of pressure to a trigger, before the weapon can be fired I do not agree with. There are different ways a person can build up their hand strength, which I personally know, having helped numerous people with that problem. Hand strength is very important in take downs and handcuffing a person who is resisting arrest. Mind ,body, manner.

  5. PhxCop

    Regarding Unintended Discharges, how difficult is it to teach officers to keep their fingers off the trigger until they intend to fire? That’s basic gun safety. With 50% UD’s happening during disassembly, it is simply carelessness. It’s difficult to fix careless.

  6. Don B

    When my agency started hiring women back in the early 90’s, we had serious issues qualifying them with our duty weapon. We also had issues with smaller handed male officers qualifying with our new duty gun.

    We carried Beretta 92’s and one size fit all!

    Our chief at the time was very old school and refused to consider letting an officer chose from several pistol options, such as the Model M single stack, or other, smaller pistols.

    It was “get them qualified or get rid of them!” We tried to explain that they more easily qualified with their off-duty weapons (as they picked their own off duty/backup weapons, which were generally smaller and fit their hands better, but our facts fell on deaf ears.).

    We worked hard and got everyone qualified, but you always went home at night hoping they would never be involved in a shooting situation!

    After I retired a new chief came on board and understood the different needs of different officers. He approved a list of five duty weapons officers could chose for on-duty carry.

    Talking to my counter parts who now do the qualifications, it’s night and day difference for the officers with their gun handling abilities and confidence in themselves!

    As an aside:
    Regarding Unintentional discharges, we had a joke in the firearms/armorer unit: officers who play with matches and get burnt usually don’t ply with matches anymore!
    Officers who play with knives and cut themselves usually don’t play with knives anymore.
    So to save officers from playing with their guns and getting hurt we’ll just go ahead and shoot them in the knee! (Remember, it’s just a joke!)

  7. I appreciate you quantifying how grip strength translates to accuracy. There is another layer to this and that is the difference between max grip intensity and an intensity that can be held for long enough to be beneficial in a shooting situation.

    As an example, let’s say that it takes roughly 60 pounds of force applied to the top rear and bottom front of the grip to be able to shoot 1/4 second splits on an 8″ target at 21 feet with a full power 9mm load. (What I’ve found using force sensors) What I’ve found is that the 60 pounds of force is connected much more tightly to the amount of grip force a shooter can exert for 1 minute than the max grip force a shooter can exert for 3-5 seconds. What this means practically is that doing 1 minute hangs or 1 minute of holding a gripmaster may be more helpful than several reps with more resistence.

  8. Alan Kerby

    Ox bring up some valid points. The problem with these grip strength shooting accuracy studies is that there are many variables that are never considered. Hand size vs grip size, grip type (monkey grip vs vice grip), pressure from 4th and 5th digits on grip and from primary or support hand, stance affects grip strength as does cant or no cant (especially single handed), how this all relates to recoil management, trigger finger placement and press pressure (which index finger articulating forearm muscles or combinations used), and many others. Changing a single variable will not produce results that can be translated to operational improvements.

  9. John Leighton-Dyson (JLD)

    This is a useful and helpful piece of work that informs the debate and as said by others is only one small part of the jigsaw about accurate shooting under pressure in a fight. The other variables are mentioned also by others and there are more still and language matters – ‘squeeze’ is to my mind inappropriate as the firer inevitably squeezes whole hand including the index finger – resulting shots often miss the threat even at close range. ‘Pull’ and ‘press’ are more appropriate? I hail from the other side of the pond where we say ‘pull’, you guys say ‘press’ both are mechanically the same thing. How the firer grips/holds the handle/weapon plays a crucial part – another huge subject as mentioned and something that is often overlooked in week 1 training – get that right from day 1 and results regardless of grip strength will be better….! How we train grip and wrist strength also required as said for cuffing, holding, restraining, baton use, etc. as well as pistol gripping. Ability to maintain hold and commit before, during and through and after the shot(s) = endurance as stated before and is also relevant in order to fire 50, 100, 150 and 200 or more rounds during a training day. How do we train that and is it something we encourage in continuation training to win the fight whenever that time comes…?
    The suggestion to lighten trigger weights is one of many solutions and there are pros and many cons…? if it leads to departments reviewing weapon type and offering options to optimise performance in the fight then that has to be positive; officer safety and public safety are paramount – how can we improve training, are we training the rights things, are we training the thing right?
    Finding the answers for all officers is a key part of the effective use of lethal force and one size definitely does not suit all…

  10. Of course, there are a lot of aspects that affect shooting performances and we need to take it into account. It is an indisputable fact that the women’s grip strength is quite less than men have but it is truly wonderful that it is not permanent and the strength training can influence this situation. I think that it is the right decision to give preference to lighter trigger pull weights because it is a necessary step which can make the shooting easier and more effective in many ways. It will give a lot of people the opportunity to get rid of problems connected with grip strength.

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