106 Years of Outstanding Performance from the .45 ACP

A 185-grain COR-BON DPX +P JHP dumped about 475 ft./lbs. of energy into two 3-gallon water jugs stacked end to end. This non-fragmenting DPX round caused water to spray at least four feet from the jug and launched the cap of the first jug 10 feet in the air. Total penetration was 14 inches.

By Dr. Martin D. Topper

The international reputation of the .45 ACP became abundantly clear to me about 15 years ago when I invited a group of Japanese visitors to shoot at the Fairfax Rod and Gun Club. As I uncased my Colt Gold Cup, a young man who spoke no English suddenly exclaimed “Colt .45!” The priceless look of excitement that came over his face when I handed him the gun turned to sheer delight as the hammer fell and the big .45 boomed.

The .45 Auto remains the gold standard for stopping power, despite the fact that it has been around for over a century. Think about that for a minute. Was your car designed 100 years ago? How about your computer? Place a call with a 100-year-old telephone and you’ll never get an operator, but point a .45-caliber 1911 at someone intending to do you harm and the result will be much different. Other cartridges have come and gone since the turn of the 20th Century, but the .45 ACP is as relevant today as it was the day John Browning designed it.



M1911A1 Pistol

This military-issue M1911A1 has a Parkerized finish and is typical of the pistols issued to American GIs from the 1920s to the 1980s.



A major reason for the .45 ACP’s success was that it came along at a time when it was sorely needed. In 1892, the U.S. Army dropped the .45 Schofield cartridge in favor of the less-powerful .38 Long Colt (.38 LC). Slightly more than a decade later, soldiers fighting to suppress the Moro Rebellion complained that the .38-caliber double-action Colt revolvers lacked close-range stopping power against the highly motivated “juramentado” rebels. As a result some “obsolete” .45-caliber service revolvers were taken out of storage and issued to troops in the field. The impression of the Army was that the .45s were more effective, and largely as a result of this experience, Capt. John Thompson and Maj. Louis LaGarde were directed in 1904 to conduct tests to select a cartridge to permanently replace the .38 LC.

Thompson and LaGarde’s tests were far from scientific by today’s standards. The research design involved using handguns of various calibers to deliver mostly torso shots to a small number of live cattle at the Chicago Stock Yards in order to learn which cartridges put the animals down fastest. The protocol also called for shooting suspended cadavers to determine which cartridges caused the most movement. Special consideration was given to shots that struck long bones. It was assumed that movement of the cadaver corresponded to “shocking power,” and therefore could predict which cartridge would have the best chance of incapacitating an enemy soldier at close range.

The results of the tests were quite subjective and they generally favored cartridges that fired heavy bullets of large caliber. Based on the data gathered by Thompson and LaGarde and the Army’s past experience with .45s, Army officials concluded that the new service cartridge should fire a bullet of at least .45 caliber that weighed a minimum of 230 grains.

About the same time Thompson and LaGarde were performing their tests, John M. Browning was working with Colt to develop a new cartridge, which he called the .45 Automatic Colt Pistol (ACP). It originally fired a 200-grain round-nose bullet at 900 fps. The .45 ACP was quickly modified to shoot a 230-grain bullet to meet the Army’s new criteria, and the final result was a cartridge that propelled a 230 grain bullet at 850 fps and delivered approximately 370 ft./lbs. of energy at the muzzle. This was a substantial improvement over the 150 grain .38 LC bullet, which exited the barrel at 777 fps and produced only about 200 ft./lbs. at the muzzle.

Colt introduced the .45 Auto cartridge in 1905 along in its M1905 single-action semi-automatic pistol. The design of the pistol went through a series of further upgrades over the next six years, ending with the creation of the pistol that we all know as the M1911. In 1924, a further series of changes were made resulting in the M1911A1, which was the standard Army handgun until 1985 when the desire to conform with NATO led the U.S. to adopt the 9mm Beretta M9. Even so, many troops prefer the .45 ACP 1911, and 1911s are still in service with special groups like the Marine Expeditionary Unit. In addition to its military use, almost every major manufacturer of handguns today makes a .45 ACP pistol.

Dr. Topper uses his Rock River Basic Carry .45 at the Weekly Informal Bullseye match

Dr. Topper uses his Rock River Basic Carry .45 at the Weekly Informal Bullseye match at the Flagler Gun Club. Even though this is primarily a carry gun, its adjustable rear sight and 4.5-pound trigger make it a nice gun for informal competitions.


Thompson and LaGarde’s tests may have been rudimentary and subjective, but laboratory research and field reports since 1904 indicate that their conclusions about the .45 ACP’s effectiveness were correct. The .45 Auto clearly is a manstopper.

To know why this load works so well, it’s important to understand how it causes incapacitation. Bullets incapacitate by causing three types of injury: crushing, tissue displacement and energy effects.

1. Crushing

Crushing is caused by direct contact of the bullet or its fragments with tissue. Many types of handgun bullets are fairly substantial in their construction and are not designed to fragment. Some, such as the Glaser Safety Slug, are intended to fragment and are specifically made for environments where the threat of collateral damage is very high. However, for general carry, a bullet that expands to about 150 percent of its original caliber and penetrates between 12 and 15 inches in 10 percent ballistic gelatin generally is often the preferred choice. This type of projectile will penetrate light barriers and still penetrate sufficiently in the target to ensure that vital structures are hit regardless of the angle of the shot.

Hollowpoint bullets for the .45 ACP usually expand to an approximate diameter of .70- to .80-inch and penetrate 12 to 15 inches in gelatin. Smaller-caliber hollowpoints, such as the 9 mm, usually expand to between .55- .65-inch and penetrate 11 to 17 inches in gelatin. Shot for shot the .45 usually causes more crush injury.

2. Tissue Displacement

The second type of injury involves damage from tissue displacement, which is caused by the bullet’s momentum and energy. When it comes to momentum, some people claim that the .45 Auto has tremendous “knockdown power.” The simple fact is that even the big .45 slug has nowhere near enough momentum to knock anything off its feet other than a small mouse. On the other hand, a .45 bullet does have sufficient caliber and momentum to cause significant fragmenting of bony tissue. A friend of mine who is an orthopaedic surgeon did a study of bone injuries caused by bullets. He found that the .45 caused larger bone splinters that traveled further from the wound track than the 9mm.

Momentum is important with respect to bone injuries, but bullet energy is responsible for most of the damage caused by tissue displacement. Energy causes a temporary cavity to form along the wound track. The shape and size of the temporary cavity and the amount of damage the cavity causes depends upon a bullet expansion, bullet energy and the type of tissue in the bullet’s path. For example, jacketed roundnose “hardball” bullets don’t expand. Therefore, they slip through tissue and transfer minimal amounts of energy. Because of this, ball ammunition creates very small temporary cavities in most tissues.

On the other hand, pre-fragmented bullets like Glasers and many hollowpoints shed most or all of their energy in the target. That energy causes the various tissues to accelerate rapidly away from the wound track. Most practical defensive handgun calibers develop muzzle energies of 150 to 550 ft./lbs. As the energy available to be transferred by a hollowpoint or fragmenting bullet increases, so do the wounding effects of tissue displacement.

The Textbook of Military Medicine (Part 1, Volume 5) divides the injuries from tissue displacement into two zones that surround the crush cavity. The closest to the crush cavity is called the “zone of extravasation.” Extravasation means that tissues have expanded so much that tiny blood vessels have been destroyed. Hunters often say tissues in this area are “bloodshot.” This zone is important to surgeons because it no longer has sufficient blood supply to heal, and therefore tissues in the zone of extravasation must be removed to prevent infection.

The “zone of concussion” surrounds the zone of extravasation. Tissues in the concussion zone are damaged by compression. Concussion can cause severe fissures in non-elastic tissues like the liver, and can shred fluid-filled organs like the bladder, even at the relatively low-energy levels generated by most common handgun defense loads. Given that some expanding and fragmenting +P .45 ACP loads develop upwards of 550 ft./lbs. of energy when fired from a 5-inch barrel, the most powerful .45 Auto loads deliver at least 10 percent more energy to the target than most other standard service cartridges.

3. Energy Effects

The third primary form of ballistic injury is due to the pulsating pressure wave generated by the transfer of bullet energy. Recent work in this area has been conducted by Drs. Michael and Amy Courtney of the Ballistics Testing Group. The results of this research indicate that a pressure wave is generated within the entire body when a bullet impacts any part of it. The pressure wave radiates outward from the site of impact and can travel to the brain where it can cause microscopic damage that can affect the functioning of the central nervous system and can cause disorientation and incapacitation.

The magnitude of the pressure wave largely depends upon the amount of energy that the bullet transfers to the body. Therefore, the more energy a projectile has, and the faster it transfers it, affects the amount of traumatic injury caused by the pressure wave. The analysis performed by the Courtneys indicates that as the energy deposited by a non-fragmenting but rapidly expanding hollowpoint bullet in the center of the chest increases from 300 to 400 ft./lbs., the probability of incapacitation from the effects of pressure-wave effects on the brain increases from about 50 to 80 percent.

The 165-grain COR-BON Power Ball fired from a gun with a 3-inch barrel deposits about 399 ft./lbs at close range, and therefore would have about an 80-percent probability of causing incapacitation due to the pressure wave when fired from a Colt New Agent. The same +P load delivers about 550 ft./lbs. from a 5-inch 1911, increasing its probability of causing incapacitation from pressure-related central nervous system trauma to over 95 percent. Given that the .45 ACP has the potential to deliver more energy to the target than other standard service cartridges, it should also have the potential to generate the strongest pressure waves.


Are some .45 Auto loads really 95-percent stoppers? Data on shooting incidents published by Evan Marshall and Edwin Sanow in their book Stopping Power indicates that the best .45 hollowpoints available at the time of their study were about 96 percent effective in producing one-shot stops. Other high-energy cartridges with hollowpoints that expand rapidly are also very effective, but the .45 had a larger number of hollowpoint loads that are over 90-percent effective than any other caliber in the Marshall and Sanow study.

Whenever discussing terminal ballistics, it’s important to remember that terminal ballistics research offers general guidelines and cannot predict the outcome of any specific armed encounter. The exact track a bullet takes through the target, the target’s general health, state of mind and the use of various drugs and medications make every shooting unique and affect the ability of an individual to withstand any of the incapacitating effects of ballistic injury. Even when a state-of-the-art .45 ACP hollowpoint is used, one can’t assume a one-shot stop will occur. Therefore, surviving an armed encounter requires the will to stay engaged until it’s absolutely certain that the threat has been neutralized.


Today’s .45 ACP defense loads are the result of a process of improvement that began to gather steam in the late 1960s when Lee Juras developed the Super Vel line of ammunition. Back then, most 1911 and .45 ACP revolver shooters had two choices: 230-grain hardball at 850 fps. and the 190-grain Super Vel load at 1000 fps.

The Super Vel load was often hard to find, but it was a decent performer and it offered controlled penetration. Unfortunately, the feed ramps of most .45 Autos at that time were designed for hardball. Super Vel and many other early hollow-point loads, such as Speer’s 200-grain”Flying Ashtray,” required “throated” barrels, and gunsmiths across the country began to modify GI and commercial 1911s to feed this new ammo. At the same time, most major bullet and ammunition companies began to develop hollowpoint designs that fed better and expanded at a broader range of velocities.

Today’s .45 shooters have a broad variety of ammunition to meet almost every conceivable defensive need. For military applications, hardball is still is the predominant choice. Enemy troops often shoot from cover and wear protective gear. Therefore soldiers need a load that penetrates deeply, and JRN ammunition penetrates best by far. On the other hand, people working behind store counters in high-crime neighborhoods often have innocent bystanders to think about. In that situation, a lightweight JHP or even a Glaser Safety Slug that penetrates less than 10″ would create less risk of collateral damage.

Of course most people are neither soldiers nor sales associates. These individuals need ammo suitable for home defense and carry on the street. Home defense and carry generally requires rapidly-expanding bullets that don’t fragment and also have controlled penetration in the 12- to15-inch range.

Recent improvements in bullet technology have led to bullet designs that reliably deliver this middle range of penetration. The first improvement was the development of bonded JHPs. Core-jacket separations were a major problem with early hollowpoints. When the jacket separates from the core, the core can fragment or deflect inside the target. Even though fragmentation causes a more rapid energy deposit, a fragmented bullet can deflect or otherwise fail to penetrate deeply enough to reach vital structures, especially when the target is hit at an angle.

Bonding the jacket and core makes it possible to build a handgun bullet with a wide hollowpoint that expands rapidly at relatively low velocity. But even though they expand quickly, bonded bullets don’t fragment even when they penetrate light cover on the way to the target. Safety glass is one such barrier. It frequently strips an unbonded bullet’s jacket and shatters its core. Although civilians don’t often need to shoot at targets behind glass, bonded bullets can be lifesavers for policemen making felony car stops and for SWAT teams facing active shooters inside office buildings and schools. Handgun bullets like the Speer Gold Dot, the Federal Tactical, the Winchester PDX-1and Remington’s Golden Saber Bonded are all excellent examples of bonded bullet technology.

The second important development is the invention of the all-copper hollowpoint. Copper hollowpoints have been around for decades, but the first widely available ones were introduced about eight years ago when Barnes Bullets and Taurus International teamed up to produce 185-grain .45 ACP “Hex” bullet ammunition. The Hex bullet got its name because the metal walls of its hollowpoint cavity peeled back into six petals.

COR-BON and Black Hills Ammunition currently produce handgun ammunition with similar Barnes copper “X” bullets. These projectiles expand readily at low velocities, and their hollowpoint cavities don’t plug up when they encounter various types of clothing. In many calibers, they also provide 12 to 16 inches of penetration in tissue while providing excellent penetration against barriers, including safety glass.

The third development involved the use of flash-suppressed powder. A large number of armed encounters occur in low-light environments, and while the .45 ACP never produced the bright fireball characteristic of higher-pressure cartridges, the introduction of flash-suppressed powders has given the .45 one of the lowest muzzle signatures of any cartridge. In a low-light confrontation, this can be a significant advantage.

The result of these improvements is that even standard pressure 230-grain .45 ACP JHPs readily expand to about .70 to .80 caliber when fired from 3-inch barrels. Even though they expand well, these loads still penetrate upwards of 12 inches when fired from the short-barreled .45s.

Expansion and penetration from pistols with Commander-length 4.25-inch and full-length 5-inch barrels is very similar. Therefore the only major difference in ammo performance between the various barrel lengths is that .45 Autos with longer barrels deliver more muzzle velocity and energy, which creates larger temporary cavities and stronger pressure waves. In the end, short-barreled .45 Autos work quite well and long ones work even better.


The .45 ACP was adopted as America’s military handgun cartridge just over 100 years ago at a time when it was clear that a lack of stopping power was placing our troops at risk. Its big, heavy 230-grain JRN bullet at 850 fps. was among the most effective handgun cartridges of its time.

Today’s improved versions of the.45 ACP are excellent performers, and there are highly-effective .45 loads available for almost every tactical need. The .45 Auto has been America’s Manstopper for over a century, and it’s likely to remain a favorite as long as Americans rely on handguns for personal defense.


Thanks to Peggy Topper, the Florida Gun Exchange and the Flagler Gun Club for help with this article. Thanks also to Federal, Black Hills, Speer, COR-BON and Remington for providing ammunition used in this story.


Black Hills Ammunition

605.348.5150; www.black-hills.com

COR-Bon Ammunition

800.626.7266; www.dakotaammo.net

Colt Firearms


Drs. Michael and Amy Courtney


Fairfax Rod and Gun Club


Federal Ammunition


Flagler Gun and Archery Club


Florida Gun Exchange

386.304.9499; www.floridagunexchange.com

Hornady Ammunition


Remington Ammunition

800.243.9700; www.remington.com

Speer Ammunition

800.627.3640; www.speer-ammo.com


Stopping Power by Evan Marshall and Edwin Sanow

800.392.2400; www.paladin-press.com


Textbook of Military Medicine www.bordeninstitute.army.mil/published_volumes/conventional_warfare/conventional_warfare.html

Winchester Ammunition


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