By Rob Shaul and Adam Scott
We spent two days this week in Fresno working with 10 members of the City of Fresno SWAT team.
The Fresno SWAT team volunteered to be our “lab rats” for a study designed to test the mission-direct effects of a lighter trigger pull.
Most stock and issued carbines come with a trigger pull of between 7.5 and 9.5 pounds. We designed to study to assess whether a lighter trigger, 4.5-5.5 pounds, had any effect on marksmanship.
Trigger-pull resistance or trigger-pull weight is the amount of force required to release or “break”
causing the hammer or striker to release and fire the weapon (10). The general consensus among experts seems to be that lighter trigger pull poundages can aid in marksmanship (6-8). Two pieces of anecdotal evidence are often cited for this conclusion: First, lighter triggers are almost universally preferred by the best competitive marksman (7). Second, and more generally, lighter resistance should, according to most marksmanship professionals, lead to easier manipulation of the fine motor skills involved in trigger control (4-6, 10).
However, to our knowledge, no formal study has yet directly examined the effect of trigger
pull resistance on marksmanship performance.
In our years of experience with Range Fitness, we’ve come to believe that trigger control is “everything.”
According to United States Marine Corps Reference Publication (MCRP 3-01A), Rifle Marksmanship, “Trigger control is the skillful manipulation of the trigger that causes the rifle to fire without disturbing sight alignment or sight picture. Controlling the trigger is a mental process, while pulling the trigger is a mechanical process.”
The importance of trigger control in marksmanship performance is cited everywhere from the US Army, to the US Marine Corps, to the Federal Law Enforcement Training Center (FLETC) (1-4, 6). MCRP 3-01A identifies it as one of three major factors which contribute to marksmanship: “the fundamentals of marksmanship are aiming, breath control, and trigger control” (2). Although it would seem to align, whether or not lighter trigger pull resistances could contribute to trigger control has yet to be determined in a scientific study.
The argument against light triggers centers on safety. Super-light triggers can be dangerous and result in Accidental Discharges (AD). We’ve seen un-confirmed reports that the minimum carbine trigger pull weight for law enforcement agencies is 4.5 pounds. Fresno SWAT did not have an official trigger pull weight minimum.
Most previous scientific studies on marksmanship have focused on “aiming” aspect of accuracy. This includes a study from the US Army Aeromedical Research Laboratory which found that visual skills and attention were the most important contributors to marksmanship (3). Other studies have also found that eye dominance and hand dominance can effect marksmanship (4), as can grip strength (13) and physical stress (5).
Anyone who has tried to make an accurate shot with a heavy trigger understands intuitively how a lighter trigger can increase marksmanship. The relatively heavy, 2-stage triggers which come with issued law enforcement and military carbines increase the time from acquired target to bullet-away. This increased time can lead the shooter to “jerk” or “push” in recoil anticipation, hold his/her breath longer, and attempt to “ambush” the target with they sights – all which can lead to missed shots. A lighter trigger decreases this time and can lead to smother, more surprise shots.
We hypothesized going into the study overall lighter triggers would improve marksmanship. However, this improvement would be most pronounced at longer distances – 50 and 100 yards.
The 10 study participants were experienced members of the Fresno SWAT team. The Fresno SWAT team is a part-time team, common to many municipalities.
We randomly separated the 10 participants into two groups of five participants each: (1) Study, and; (2) Control.
The study subjects completed a total of 60 marksmanship trials, 20 each at 15 yards (standing), 50 yards (standing) and 100 yards (kneeling.).
Ten trials at each distance were non-stress. Each trial, the study subjects had to fire 6 shots, 3 each at two targets separated by approximately 3 feet.
Ten were “stress” where the participants had to run 2x 15-yard shuttles, retrieve their weapon from a table and fire 6 shots at 2x targets (3-shots each), again separated by 3 feet. The time limits were: 15 yards (20 seconds); 50 yards (25 seconds); 100 yards (30 seconds.)
Targets were B-29 Law Enforcement Qualification Targets.
Each group shot the first 30 trials with stock triggers. Stock trigger pull weights were measured using a Lyman Electronic Digital Trigger Pull gauge. Each trigger was measured three times, and the three measurements were averaged.
At each distance (15/50/100 yards), the study subjects shot 5 trials (30 bullets) non stress and 5 trials stress. Targets were scored and replaced after the each 5 trials.
After the first 30 trials, the triggers in the Study Group’s weapons were replaced with Hiperfire EDT2 triggers following the manufacturer’s instructions. After trigger replacement, the Control Group’s triggers were again measured and the average pull weight was 5.05 pounds.
Both groups then shot 5 trials at 15 yards – to give the control group some experience with the new triggers. Then both groups re-shot the entire 30 trials.
Overall, the Study Group’s (light triggers) marksmanship improved 7% using the light triggers compared to the Control Group’s 4% overall improvement the second time around.
However, at the longer distances, 50 and 100 yards, the Study Group’s marksmanship improved 15% compared to the Control Group’s 8% improvement.
These are just initial results, and a comprehensive statistical analysis is forthcoming.
1. Headquarters Department of the Army. U.S. Army Field Manual 3-22.9 – Rifle Marksmanship M16-/M4- Series Weapons. Washington, DC, 01 FEBRUARY 2011.
2. Headquarters, United States Marine Corps, Department of the Navy. Marine Corps Reference Publication (MCRP) 3-01A, Rifle Marksmanship. Washington, DC, FEBRUARY 1999.
3. Kelly, A., Athy, J., King, M., Erickson, B., Chiaramonte, J., Vasbinder, M. and Thompson, A. Think before you shoot: The relationship between cognition and marksmanship. United States Army Aeromedical Research Laboratory – Warfighter Health Division. USAARL Report No. 2011-23. 2011.
4. Jones, L., Classe, J., Hester, M., and Harris, K. Association between eye dominance and training for rifle marksmanship: a pilot study. J Am. Optometric Ass. 67(2): 73-76, 1996.
5. Frykman, P., Merullo, D., Banderet, L., Gregorczyk, K. and Hasselquist, L. Marksmanship deficit caused by whole-body lifting tasks with and without torso-borne loads. J. Str. Cond. Res. 26: S30-S36, 2012.
6. Tarr, J. What’s the right trigger pull weight for a carry gun? Guns & Ammo Network. Available at: http:// www.gunsandammo.com/. Accessed: 20 November, 2015.
7. Cowan, A. The truth about trigger weight: Part 1 of 2. Breach and Clear. Available at: http:// www.breachbangclear.com/a-critical-look-at-trigger-pull/. Accessed: 20 November, 2015.
8. Patrick, C., et al. A continuing story of firearms simulation. Federal Law Enforcement Training Journal. 11: 8-10, 2103.
9. The Federal Bureau of Investigation. Uniform Crime Reports. Available at : https://www.fbi.gov/about-us/ cjis/ucr/ucr-publications. Accessed: 21 November, 2015
10. Dolbee, D. Trigger Pull Weight. National Shooting Sports Foundation. Available at: http:// www.nssfblog.com/firstshotsnews/trigger-pull-weight/. Accessed: 21 November, 2015.
11. Kreider, J. Trigger Pull Testing M16A2 Rifle & M4 Carbine – Final Report. US Army Small Arms Branch. Technical Report Number: SMCAR-ES-93-1. 1993.