SIGHTING IN ON: Understanding Bullet Performance
Physics are scientific laws. You can’t break them to get a bullet to perform.
By Duane Wolfe
I had the opportunity to attend the Special Operations and Tactics Association (SOTA) Annual Conference. As part of the training, Johann Boden from ATK (parent company of Speer and Federal ammunition) was on hand to conduct a wound ballistic workshop. Prior to joining ATK, Boden served with the German GS5 where he performed high-risk warrants and urban anti-terrorism operations. He emigrated to the U.S. and served with the U.S. Marine Corps. He then served four years as an Anti-Terrorism Operations Liaison for the U.S. and German military.
Despite Boden’s position as a sales rep for an ammo company, the first thing he told us, and continued to remind us of, was that pistol ammunition is a lousy fight stopper. He gave good information and advice for anyone making ammunition selection decisions for a police department.
What’s Most Important?
The most important factor to incapacitate a suspect is shot placement. What the bullet hits is critical to making a suspect stop their deadly assault. Boden reminded us that pistols do not usually have the ability to instantly incapacitate a suspect. It will take anywhere from 10-15 seconds or longer, depending on what part of the body is hit.
The depth that the bullet penetrates is absolutely critical in reaching vital organs. That depth can vary depending on the angle that the bullet enters the body. A few inches through the sternum or over 12 inches for a round that enters the arm, traverses through the rib cage, lungs and heart of a large subject. The FBI Protocol requires that bullets penetrate to a depth of 12-18 inches in gelatin to demonstrate adequate penetration in a shooting.
Penetration is determined by bullet mass and design, NOT by velocity. This came as a surprise to me. Boden explained that as velocity increases, the bullet will open sooner, slowing it down and in many cases causing the higher velocity round to penetrate less deeply. So a +P or +P+ round may give shallower penetration along with more recoil than a standard velocity round.
The speed that a bullet travels CAN be important. Rifle rounds traveling over about 2,200 feet per second (fps) attain hydrostatic shock, which increases and disperses a shock wave through the body since it consists mostly of water. This means that the bullet can cause additional damage to other organs along the bullet path.However, if the speed is below 2200 fps, the damage will be limited to the wound channel caused by the bullet. Handgun rounds run between 850-1400 fps.
I’ve already mentioned the effect or lack of effect that +P and +P+ rounds can have on penetration. The Mark Coates shooting showed us a perfect example of lack of penetration killing power. During that incident, Trooper Mark Coates shot a suspect five times at a close distance. All of the rounds from his .357 revolver failed to reach the vital organs of an obese killer. Coates was shot several times by a .22 mini revolver. Unfortunately, not all of the rounds struck his vest. One hit his left upper arm, turned and followed the bone into the chest cavity, and he died on scene. The suspect survived to stand trial.
Carrying a submachine gun in your squad? The rounds in your gun may have been tested in a pistol according the FBI or Border Patrol testing protocol and proved adequate to the task. Put that same round into a sub gun with a longer barrel, which will result in higher velocity, and the results may change dramatically. The bullet designed to expand and penetrate adequately at pistol speed may now break up on impact and/or lose penetration, potentially resulting in a failure like the Coates shooting. If you’re carrying a sub gun, has the ammo been tested at those velocities?
Physics Are Scientific Laws; You Can’t Break Them
Repeat after me, knockdown power does not exist! Newton’s law tells us that for every action there is an equal and opposite reaction. Forget Hollywood and TV because bad guys won’t fly backward due to bullet impact. Johan gave the example whereby a 9mm has the impact of a 10-pound weight dropped from a height of ¾-inch. A .45 ACP has the impact of a whopping 1.1 inches.
As velocity increases, so does recoil. How is your recoil control with your weapon? When you shoot your firearm are you controlling the weapon? When you shoot your pistol, does the slide come straight back and then go forward with no lift in the muzzle? Or do you have to force the muzzle back into sight alignment between each shot?
As a firearms instructor, I would make several suggestions on how to control the gun. Make sure both of your arms are straight. This keeps the elbows from flexing and causing rise. A firm grip and locked wrists contribute to hanging on to the gun with as much of your hand on the grip as you can get. Recoil will move in the direction of least resistance. If there is a gap in your grip, then that is the direction the recoil will go. When you shoot one handed with your strong hand, the gun lifts up and to the left, demonstrating physics in motion. Any bent joint, such as your wrist or elbow, will allow a recoil leak and can cause a malfunction if the semi-automatic pistol isn’t held in place.
Bring the gun out toward the target at shoulder level and lower your head to the gun. When the gun is above shoulder level, the angle acts like a lever and causes the gun to rise. Straight arms that lead directly back into the torso allow the recoil to travel directly into the body. That mass is greater than the recoil of the pistol and it allows the rearward impulse to be dispersed by it. Dropping your head down and forward takes a 20-pound weight and brings it into the game just like the body, reducing felt recoil. Leaning forward slightly brings the torso in play to take up recoil even more. Watching Johan shoot into the ballistic gel reconfirmed these shooting basics. Even though he was only firing one round at a time, his years of training and recoil control were evident every time he pressed the trigger.
Why is recoil control critical control? In gunfights, cops fire around 5-8 rounds per second according to the research conducted by the Force Science Institute. If you’re shooting that fast and your muzzle is lifting each time, then where will your second, third, and subsequent shots be going?
When you train, do you shoot slowly for score? If you are training for a gunfight, you better pick up the pace and practice at combat speeds of around five rounds per second or more. You may be in for an unpleasant surprise on the street if you practice too slowly.
Boden further explained that recoil is measured in Kinetic Joules (kj). He explained the difference in recoil between a .40 and a .45. Both of them have 35 kj of recoil. The difference is the .40 releases that energy in 2/10 of a second and the .45 in 4/10 of a second. He explained that is why the .40 has a much sharper recoil snap while the .45 has more of a push, making it easier to control.
Big Bullets Make Big Holes
Unless you make a Central Nervous System hit, which will result in an instant stop, the bad guy will have to collapse from loss of blood. Bigger holes drain liquid faster and that is one of the purposes of a bullet that expands, to create a bigger hole.
Boden explained that the FBI protocol required bullets to expand to 1.5 times their original diameter. He gave the following information as examples of caliber designation, actual bullet diameter, and expansion after FBI protocol firing:
You will notice there isn’t a whole lot of difference between the calibers, especially the 9 mm, .357, and .40. Johan then posed the question that if the expansion is basically identical and the penetration is about the same, then what is the benefit of a weapon that has more recoil like the .357 Magnum and .40 S&W? He also noted the increased wear and tear on the gun because of the high velocity and the increased cost of ammunition.
Based on Boden’s expertise, the .45 is recommended for those shooters who are comfortable with a gun that has a larger frame and a smaller round capacity. The 9mm is recommended for those who want higher capacity and a smaller frame size.
The Proof is in the Gelatin
After Boden’s lecture portion was completed, the class headed to the range where gelatin blocks would be fired upon to demonstrate penetration, expansion and bullet performance. ATK only shoots Federal and Speer ammunition during the test but will allow officers to bring in their own ammunition to fire. On their website www.le.atk.com, ATK posts the results of different Wound Ballistics Workshops conducted over the years and you might find your own ammunition’s results.
During the testing, we saw bullets fired into bare gelatin, through clothing, sheet rock and auto glass, per the FBI Protocol. The Protocol is explained in detail at the ATK LE website. A crowd of over 40 officers packed the indoor range during the testing. There would have been even more if the class size had not been limited.
A combination of .380 ACP, 9mm, .40 S&W and .223 Remington ammunition was tested as several officers provided their own ammunition for comparison in the gelatin. The testing provided some startling results for a few of the officers. As already mentioned, pistol ammunition fired out of a submachine gun showed a dramatic reduction in penetration.
The most dramatic results came when shooting the .223 ammo out of a patrol rifle. Several brands of hollow points and/or polymer inserts in the tips did not penetrate the gel to the designated depth required and performed even worse when passing through barriers like auto glass. These rounds were originally designed as varmint rounds. The bullet was meant to shoot 20-pound rodents and expand dramatically. However, when used against 200-pound humans, their rapid, almost explosive expansion failed to penetrate deeply enough to hit the vital organs. The theory behind their use and development for LE was to reduce the likelihood of over penetration. However, in the real world, the hollow point design resulted in a lack of meaningful penetration.
Auto glass proved to be the toughest barrier due to its lamination. Some bullets broke up completely, with a resulting loss of penetration. Boden advised that beginning in 2012, all glass used in cars will be laminated. Prior to 2012, only the front and rear windows were laminated. If the side windows of a car were shot at, they would shatter and additional bullets could pass through with little effect on the bullet. This is an important tactical tip to keep in mind when dealing with vehicles in the future.
Also present during the testing was Dr. James Williams, a surgeon and Head of Emergency Medicine, who runs the “Tactical Anatomy Systems” training program. Dr. Williams also taught a class at the conference on using anatomical knowledge when shooting entitled, “Tactical Anatomy.” With his knowledge of emergency medicine and having seen the results of gunshot wounds up close and personal as a surgeon, he was a valuable asset to the training. He agreed with Boden’s conclusions throughout the ballistic testing.
For whatever reason, duty weapon caliber continues to be a hot debate topic in law enforcement circles and I don’t think that will change anytime soon. Ammunition has changed dramatically in the last 10 years. However, not everyone is aware of the changes and their opinions may be based on outdated information. This training provided officers an opportunity to see the results of bullets utilizing the FBI Protocol for themselves. I know that all of the officers found it interesting and informative and that more than a few of the SWAT cops will be attempting to make changes in their departments’ choice(s) of ammunition.
Personally, I carry Federal 147-grain HST in my Glock because I am faster and more accurate with a 9mm than a .40 S&W. I have small hands, so a large frame doesn’t fit me well. When I started in this profession many years ago, I carried a .45 ACP, first chambered in a 1911, then in a S&W 4506. Both of those weapons had a single stack magazine that fit my hand.
I prefer carrying as many bullets as possible and a double stack magazine in 9mm fits my hand the best. I know of a number of large agencies that regularly engage in multiple gunfights each year and they have found the round to be very effective. Based on that, Boden’s recommendations, and the ballistic results seen at the workshop, I will continue to carry the HST 9mm with confidence. PM
Duane Wolfe has a BS in Criminal Justice and an MS in Education. He recently retired after 26 years as a police officer. He has been a full time trainer for the last 20 years. He is a firearms and Use of Force instructor.
- The effects of auto glass on bullet performance (left to right): 9mm, .40, .45
- Bullets fired through two layers of denim cloth over ballistic gel. When the cloth gets stuck in the base of the hollow point, it can cause bullets to act like full-metal jacketed rounds when shot through cloth, sheet rock or metal.
- .45 JHP vs .45 FMJ, the expansion of the JHP creates a larger wound channel and controls penetration. FMJ rounds have a tendency to go through the target due to a lack of expansion.