45 Long Colt vs 45 ACP | The Ultimate Caliber Face-Off

Exploring the world of firearms and ammunition can be both intriguing and complex, especially when it comes to understanding the differences between seemingly similar cartridges. 

When discussing legendary handgun ammunition, two calibers often come up: the 45 Long Colt (LC) and the 45 Automatic Colt Pistol (ACP). 

Despite their similar nomenclature, these two iconic cartridges have distinct histories, applications, and functionalities. 

45 Long Colt vs 45 ACP Showdown: The Ultimate Caliber Face-Off

The 45 LC, a storied revolver cartridge, and the 45 ACP, primarily used in semi-automatic pistols, have each carved their unique paths through American firearms history. 

.45 Long Colt Ammo

It is important to note that despite the presence of “Colt" in the names of both the .45 Long Colt (sometimes referred to as .45 LC) and .45 ACP (Automatic Colt Pistol), these two cartridges are distinct and serve different purposes.

45 Long Colt, 185 grain JHP

at HOP Munitions
Prices accurate at time of writing

Going back to 1872, Colt, a prominent firearms manufacturer, joined forces with the Union Metallic Cartridge Company (UMC) in a collaborative effort. They aimed to develop a new cartridge that would meet the requirements of the U.S. Army. This partnership led to the creation of the .45 Long Colt ammunition. Often abbreviated as .45 LC, this cartridge was formally adopted by the Army in the subsequent year.

The .45 Long Colt was specifically designed for use in revolvers, such as Colt’s Single Action Army (also known as the Colt Peacemaker). It featured a relatively long case and a moderate charge, making it well-suited for use in single-action revolvers of that era. The cartridge quickly gained popularity and became synonymous with the iconic revolvers of the Old West.

On the other hand, the .45 ACP (Automatic Colt Pistol) was developed by John Browning in 1904, as mentioned earlier. Despite the inclusion of “Colt" in its name, this ammunition was not created by Colt, but rather by Browning, who was working for Colt at the time. The .45 ACP was designed specifically for semi-automatic pistols, including Browning’s groundbreaking M1911.

The .45 ACP and .45 Long Colt differ in several aspects, such as case length, bullet shape, and intended use. The .45 Long Colt, with its longer case, was primarily intended for revolvers, while the .45 ACP was designed for semi-automatic pistols. Each cartridge was tailored to meet the specific requirements and operational characteristics of the firearms for which they were intended.

.45 ACP Ammo

During the course of firearm development, an influential moment came with the creation of the .45 ACP (Automatic Colt Pistol), which is also commonly referred to as .45 Auto. This ammunition was introduced in 1904, and it is worth noting that its name might lead one to assume it was developed by Colt. However, it was the result of the innovative work of John Browning, even though Colt employed him at the time.

45 Auto, 230 grain JHP

at HOP Munitions
Prices accurate at time of writing

John Browning, a renowned firearms designer, played a significant role in the evolution of firearm technology. In 1904, he introduced the .45 ACP, which would go on to become an iconic and widely used cartridge. It is interesting to note that despite working for Colt, Browning’s inventive mind led him to design and develop this ammunition independently.

The .45 ACP cartridge was specifically engineered to meet the requirements of the U.S. Army, which sought a powerful and reliable round for their semi-automatic pistols. Browning’s expertise and deep understanding of firearm mechanisms allowed him to create a cartridge that successfully combined stopping power, accuracy, and reliability.

45ACP Ammunition
Several .45 ACP variants: hollow point, full metal jacket, WWII-era military issue birdshot/Photo Credit: Derek280/Wikimedia Commons

As a testament to its effectiveness, the .45 ACP quickly gained popularity and widespread adoption. It became synonymous with iconic firearms, most notably Browning’s own creation, the M1911 pistol. This legendary handgun, chambered in .45 ACP, went on to become the standard-issue sidearm for the U.S. military for several decades.

In summary, the development of the .45 ACP ammunition by John Browning in 1904, although working for Colt at the time, marked a pivotal moment in firearm history. Its creation fulfilled the army’s requirement for a powerful and effective cartridge, and it went on to leave an indelible mark in the world of firearms.

45 Long Colt vs 45 ACP: Ballistics Comparison

The ballistics of the .45 Long Colt and .45 ACP, particularly in the 185-grain Jacketed Hollow Point (JHP) variety, can be compared based on their respective velocity and energy.

.45 ACP 185gr JHP

  • Velocity: The .45 ACP (Automatic Colt Pistol) round offered by HOP Munitions has a velocity of 950 feet per second (FPS). This is a typical velocity range for the .45 ACP, especially in its 185gr JHP configuration.
  • Energy: The energy output for this round is stated as 370 foot-pounds (ft/lbs). This energy level is significant for a pistol cartridge and is indicative of the .45 ACP’s renowned stopping power.
  • Effective Range: The .45 ACP is known for its significant energy at close ranges, maintaining at least 300 ft lbs of energy at 100 yards. However, due to its slow muzzle velocity, the trajectory is not flat, with an average bullet drop of 15 to 20 inches at 100 yards​​. This suggests that while the .45 ACP can be effective at 100 yards, it is more suited for shorter distances where its stopping power can be maximized without substantial compensation for bullet drop.

.45 Long Colt 185gr JHP

  • Velocity: The .45 Long Colt variant from HOP Munitions has a velocity of 1,000 FPS. This is notably higher than some traditional .45 Long Colt loads, reflecting advancements in ammunition technology and a focus on achieving more velocity than previous heavier bullet loads like the 250gr JHP version.
  • Energy: The energy for the .45 Long Colt round is listed as 411 ft/lbs. This higher energy level compared to the .45 ACP is a result of the increased velocity, contributing to its effectiveness, particularly in a self-defense context.
  • Effective Range: Determining the effective range of the .45 Long Colt, particularly with the 185gr JHP load, is a bit more complex. The traditional .45 Long Colt loads are considered effective up to 100 yards, as indicated by historical use and ballistics data​​. However, for modern loads, especially those with lighter bullets like the 185gr JHP, the effective range may differ. While specific data for the 185gr JHP was not readily available, it’s reasonable to assume that the effective range could be slightly extended compared to heavier bullet loads, considering its higher velocity. Anecdotal discussions suggest that with good accuracy and under ideal conditions, the .45 Long Colt in various loadings could be effectively used at ranges up to 120 yards or more, although practical use in hunting or self-defense scenarios might limit this range​​.

Comparison Summary

Velocity: The .45 Long Colt 185gr JHP has a slightly higher velocity than the .45 ACP 185gr JHP (1,000 FPS vs. 950 FPS).
Energy: Correspondingly, the .45 Long Colt also has a bit more energy (411 ft/lbs vs. 370 ft/lbs).

While both cartridges are effective for self-defense, their historical contexts differ: 

The .45 ACP is closely associated with military and law enforcement use, especially in semi-automatic pistols like the M1911, whereas the .45 Long Colt has a storied history in the American West and is traditionally used in revolvers.

Both cartridges reflect a blend of historical significance and modern ballistic performance, with each offering unique advantages depending on the user’s needs and preferences.

The U.S. Army Transitions from .45 LC to .45 Auto

The reason the army chose to adopt a semi-automatic pistol while still desiring the power and accuracy they had with their revolvers was due to their reliance on the findings of the Tompson-LaGarde tests.

These tests provided crucial information that guided the army’s decision-making process. Consequently, they determined that the most effective option for their needs was the .45 caliber ammunition.

To maintain the desired stopping power and precision, the Army decided to stick with the .45 ACP (Automatic Colt Pistol) cartridge for their semi-automatic pistol. This cartridge was specifically designed to meet their requirements.

Ultimately, the firearm that met their specifications and incorporated the .45 ACP ammunition was Browning’s 1911 pistol, which was subsequently chosen as the standard issue sidearm for the Army.

Bowning 1911 Set

Prices accurate at time of writing

RELATED – 5 Best 1911 Pistols For Your Money

.45 LC vs. .45 ACP

What else is different besides manufacturers of the time? Well, visually, they also look different. The .45 Long Colt looks longer than the ACP. And the LC has a .452" diameter bullet over the .451" diameter of the ACP bullet.

There are some other, less exciting details, and I might lose some of our newer shooters here, but the grain, muzzle velocity, and muzzle energy are different too.

.45 Long Colt Specs

  • 250-grain bullet
  • 860 fps muzzle velocity
  • 411 ft/lbs muzzle energy

.45 ACP Specs

  • 230-grain bullet
  • 850 fps muzzle velocity
  • 369 ft/lbs muzzle energy

RELATED – Top Picks for the Best Lever Action Rifle Round: Ultimate Hunting Performance

Which is more powerful, .45 Long Colt or .45 ACP?

So, what do all those numbers translate into? It means Long Colt is more powerful than ACP. This presents a new question, why go to a .45 ACP when you get more power shooting .45 LC?

The answer was that it’s easier and quicker to reload a semi-auto when you’re rushed than it is a revolver. This is why, even today, the semi-auto is generally favored over the revolver.

Often laughed at, but a reason nonetheless is the additional round capacity. You get a load of 7 in 1911 magazines over the 6 shots in revolvers. 

What are the Different Names for .45 ACP?

At first, hearing about .45 ACP, it’s easy to think using the term .45 auto is just a shortening of saying the entire thing. But, that’s not entirely true.

It might be why you or your gun buddies say it that way, but there’s an actual reason other than the simplicity, and that has to do with something known as SAAMI.


SAMMI stands for Sporting Arms and Ammunition Manufacturers’ Institute. They standardize the shooting industry. And since they’re in the business of standardizing, you can imagine that they probably have multiple rules.

One of those rules is that they don’t accept trademarked cartridge names. But, that doesn’t mean they won’t accept an identical product with a non-trademarked name.

For instance, and how we get back into ACP, SAAMI wouldn’t accept the Copywrite, .45 ACP, but they would consider a .45 automatic or .45 auto because there’s no Copywrite attached to it.

International .45 ACP Names

The .45 ACP (Automatic Colt Pistol) cartridge, commonly known by various names, has different designations depending on the geographical region. In the United States, the most prevalent and widely recognized names for this ammunition are .45 ACP, .45 Auto, or .45 Automatic. These names have become deeply ingrained in American firearm culture and are commonly used by enthusiasts, professionals, and manufacturers.

However, if one were to explore beyond the borders of the United States, alternative designations for the .45 ACP can be encountered. For instance, in metric measurement systems, the cartridge is often referred to as 11.43×23 mm, reflecting the dimensions of the cartridge case and overall length. This metric nomenclature precisely describes the cartridge’s physical characteristics and is commonly used in regions that adhere to metric standards.

Additionally, some regions may use variations of the metric designation, such as 11 mm 43 or 11.25mm, to refer to the .45 ACP cartridge. These alternative names further emphasize metric measurement and are employed in countries where metric units are the standard.

It is worth noting that these variations in naming conventions do not indicate any substantial differences in the cartridge itself. Regardless of the name used, the ammunition remains the same 45 ACP round, designed to be used in semi-automatic pistols chambered for this specific caliber.

The .45 ACP cartridge is recognized by multiple names, with .45 ACP, .45 Auto, and .45 Automatic being the most common in the United States. However, when exploring international contexts, one may come across alternative designations such as 11.43×23 mm, 11 mm 43, or 11.25mm. These variations highlight the use of metric measurements and reflect the diverse terminology used in different regions across the globe.

Can You Shoot .45 ACP and .45 LC Through the Same Firearm?

The most important thing you need to take away from this article is that .45 Long Colt and .45 ACP are NOT interchangeable. LC is meant for your revolver, and ACP is intended for your semi-auto.

It’s never a good idea to try and shoot ammunition through a weapon that it isn’t designed to fire. Depending on the caliber, you could severely damage your gun or yourself. For instance, trying to shoot a .44 magnum through your .45 colt could blow your gun up.

Please keep in mind, even if a cartridge fits, that doesn’t mean you should load it.


The .45 Long Colt, with its longer case and moderate charge, found its niche in the realm of revolvers. It became synonymous with the legendary single-action revolvers of the Old West and remains a favorite among enthusiasts of historical firearms. Its rich history and association with the frontier era evoke a sense of nostalgia and admiration for classic American craftsmanship.

On the other hand, the .45 ACP, born out of John Browning’s ingenuity, was tailored specifically for semi-automatic pistols. This cartridge offered a balance of power, reliability, and magazine capacity, making it ideal for military and law enforcement use. The .45 ACP gained significant recognition through its association with the iconic Browning M1911 pistol, becoming a symbol of American military prowess and a trusted sidearm for generations.

While the .45 Long Colt and .45 ACP share the common thread of “45" in their names, they are distinct cartridges developed for different firearms and operational contexts. Each cartridge has its own devoted following, drawn to the unique characteristics and historical significance of its chosen caliber.

Table of Contents

  • .45 Long Colt Ammo
  • .45 ACP Ammo
  • 45 Long Colt vs 45 ACP: Ballistics Comparison
  • .45 ACP 185gr JHP
  • .45 Long Colt 185gr JHP
  • Comparison Summary
  • The U.S. Army Transitions from .45 LC to .45 Auto
  • .45 LC vs. .45 ACP
  • .45 Long Colt Specs
  • .45 ACP Specs
  • Which is more powerful, .45 Long Colt or .45 ACP?
  • What are the Different Names for .45 ACP?
  • International .45 ACP Names
  • Can You Shoot .45 ACP and .45 LC Through the Same Firearm?
  • Conclusion

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