45 GAP vs 45 ACP: .45 Caliber Pistol Cartridge Clash

By Wes Littlefield

Last Updated: Nov 13, 2024

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Wes Littlefield

Guns have fascinated Wes since pulling the trigger on his BB gun as a kid. He built a private gun range over a decade ago to keep his skills sharp. He loves breaking down complex ideas into understandable pieces for readers, with expertise in hunting and all aspects of shooting.

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Wes Littlefield, "45 GAP vs. 45 ACP: What’s the Difference?"
(https://ammo.com/comparison/45-gap-vs-45-acp)

Many have tried – and all have failed – to replace the legendary .45 ACP round. Discover why the 45 Automatic Colt Pistol cartridge reigns supreme when we compare and contrast it to 45 GAP in real-world scenarios.

We’ll pit the cartridges head-to-head, comparing recoil, accuracy, stopping power, self-defense, overall cost and availability, and reloadability.

Let’s get started with the differences between these .45 cal cartridges.

What’s the Difference Between 45 ACP and 45 GAP?

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The 45 ACP and 45 GAP are not the same cartridge. There are significant differences between the two.

The 45 Glock Automatic Pistol cartridge was designed to fill the void between the 45 ACP and 9mm. Firing virtually the same diameter bullet as the 45 ACP, the 45 GAP maintains similar energy levels while taking advantage of a smaller case length, making it perfect for concealed carry in compact pistols.

Just how much more compact is the 45 GAP round compared to the 45 ACP? Continue reading to find out!

Cartridge Specs

Since the 45 GAP was based on the 45 ACP, we can expect some similarities, such as similar bullet weights (165 grain to 230 grain for 45 GAP, and 68 grain to 300 grain for the 45 ACP – although most are 185 grain to 230 grain) and diameters (0.451 in for the 45 GAP and 0.452 in for the 45 ACP).

The most significant difference in size is in the case length. The 45 GAP has a shorter 0.755 in case, whereas the 45 ACP is 0.898 in. This translates into a longer overall length for the 45 ACP (1.275 in compared to 1.070 in).

To maintain similar ballistic performance, the creator of the 45 GAP cartridge (Ernest Durham) designed it with a higher maximum pressure. The 45 GAP has a max pressure of 23,000 psi; the 45 ACP has 21,000 psi.

Let’s see how these specifications affect real-world performance.

Recoil: 45 GAP vs. 45 ACP

Recoil is an important consideration when purchasing a new self-defense handgun. A round with heavy recoil is more challenging to control and will slow your follow-up shots.

Muzzle velocity (fps), bullet weight, propellant charge weight, and handgun weight all determine recoil. Felt recoil varies from shooter to shooter and cannot be objectively measured. Recoil energy, on the other hand, is quantifiable.

The recoil energy of the 45 ACP is generally 7-8 ft-lbs, depending on the exact load and firearm. The recoil energy of the 45 GAP is around 8 ft-lbs – again depending on your chosen load.

While you might notice a slight difference in recoil, these cartridges kick pretty much the same. This section is a tie because the difference in recoil is so minor.

Accuracy

It should go without saying that we want the most accurate round possible, especially in a home defense situation. Many factors contribute to a cartridge's accuracy, such as the recoil, trajectory, shooter, firearm, and shooting conditions.

For instance, it’s much easier to be accurate with a 45 ACP carbine than a 45 ACP pistol, even when using the same ammo because of the carbine’s longer barrel.

When all the controllable factors are as equal as possible, shooters will have difficulty determining which .45 caliber handgun cartridge is more accurate.

This section is a tie because both cartridges can be very accurate in the hands of a capable shooter.

Stopping Power: 45 ACP vs. 45 GAP

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If you want to start an argument at the gun store or on a gun forum, mention stopping power. It is unquantifiable, as it is ultimately determined by shot placement. A well-placed shot with a small (less powerful) cartridge will always be more effective at stopping a threat than a poorly placed shot with a larger (more powerful) cartridge.

We can argue about bullet hole size, penetration depth, and energy transfer capabilities until we’re blue in the face and still disagree. Luckily, these two cartridges typically use the same bullets at similar velocities, making them simple to compare.

The 45 ACP has a slight edge when firing lighter projectiles, but the roles are reversed when using heavier bullets. However, neither cartridge jumps way ahead of the other in either scenario.

This section is also a tie. With proper shot placement, both cartridges have very similar stopping power.

Hunting

Neither cartridge was designed for hunting, but the 45 ACP is occasionally used for bear defense and dispatching wild hogs.

Besides carrying a backup pistol for defense, I don’t recommend hunting with either cartridge. If I were forced to choose between the 45 GAP and 45 ACP, I would choose the 45 ACP because there are many more firearm and ammo options on the market.

The 45 ACP wins this section by a slight margin.

Self-Defense: 45 Glock Auto Pistol vs. 45 Automatic Colt Pistol

We’re finally at the section where both cartridges shine – but which shines brighter?

The 45 GAP was designed as the ultimate concealed carry cartridge. It fits in more compact pistols, which are easier to conceal without printing, and it doesn’t sacrifice stopping power.

The 45 ACP has been time-tested through multiple wars and utilized by law enforcement and civilians to stop threats for decades.

While the 45 GAP initially looked like it could overtake the 45 ACP, it didn’t offer shooters enough justification to switch. It died off almost as quickly as it exploded onto the scene, as did ammo and firearm options.

The 45 ACP won this section because it’s proven itself throughout history, and the countless ammo and gun options mean you can find the perfect 45 ACP setup.

Cost & Availability

If you’re scanning this article, you probably missed that the 45 ACP has a much more comprehensive selection of guns and ammo. But I’m sure you could have guessed that by checking at your local gun store.

The price of firearms is very similar, but only Glock currently manufactures firearms chambered in .45 GAP, whereas virtually every US firearm manufacturer known to man produces a gun chambered in .45 ACP. Springfield Armory had an XD series pistol chambered in .45 GAP but discontinued it after low demand.

The 45 ACP takes another leap ahead of the 45 GAP regarding ammo cost and availability. Not only is 45 ACP ammo more abundant, but it also offers more bullet options and is less expensive for comparable loads.

The 45 ACP wins this section by a landslide.

Reloading

Reloading is the way to go if you’re looking to save money on ammo or craft the perfect round for your firearm. Handloading allows you to dial in the ideal combination to get the ultimate performance out of each round.

While purchasing the reloading equipment and supplies is costly initially, your savings drastically increase when purchasing bulk ammo and reloading the spent casings.

The 45 ACP is more accessible for reloading in the sense that there are more load data and supplies available, but the 45 GAP can be reloaded, too. Reloading is often the only way you’ll have ammo on hand for the .45 GAP.

This section is a tie, as both cartridges can be reloaded with roughly the same effort.

45 GAP vs. 45 ACP Ballistics Tables

We finally made it to the section that all the number crunchers love: the ballistics section. The team at Ammo.com has compiled the ballistics of each cartridge in easy-to-read tables so you can quickly compare how similar these .45 caliber cartridges are to one another.

45 GAP Ballistics Tables

45 ACP Ballistics Tables

Don’t miss these 45 ACP ballistics tables for a deeper dive into 45 ACP performance.

45 GAP Brief History

Glock set out to make a .45 caliber cartridge that could be used in a compact handgun without an oversized grip. This allows the handgun to be carried concealed and used comfortably by most shooters. In 2003, Glock released the Glock 37 and collaborated with Speer to create the ammo.

The public’s initial response to the 45 GAP was generally positive, and a few other firearm manufacturers besides Glock produced .45 GAP pistols. However, as time passed, many 45 GAP firearms were discontinued, and Glock is currently the only manufacturer of 45 GAP handguns.

Today, a few law enforcement agencies still issue 45 GAP pistols, but most have switched back to 9mm, 45 ACP, or 40 S&W. Though the 45 GAP has similar ballistics to the 45 ACP, it is nowhere near as popular among the average shooter.

45 ACP Brief History

Created in 1905 by John Browning, the 45 ACP is an iconic American cartridge and was popularized in Browning’s classic Colt Model 1911 pistol.

The 45 ACP was initially designed to meet the U.S. Cavalry's need for a more effective round. The M1911 became the official sidearm of the U.S. Armed Forces in 1911. Favored by units like the LAPD SWAT and FBI Hostage Rescue Team, the versatility and effectiveness of the 45 ACP continue to make it a trusted choice over a century after its creation.

Today, it’s as popular as ever – with military, police, and civilian shooters. Few other cartridges sell more rounds in the US than the 45 ACP.

Frequently Asked Questions

The team at Ammo.com has gathered and answered some of the most commonly asked questions regarding 45 GAP vs. 45 ACP.

Is 45 GAP more powerful than 45 ACP?

No, 45 GAP is not more powerful than 45 ACP.

Can you shoot .45 ACP in a .45 GAP?

No, you cannot shoot .45 ACP in a .45 GAP pistol.

What are the ballistics differences between 45 GAP and 45 ACP?

The ballistic differences between 45 GAP and 45 ACP are minimal, as Glock and Speer designed the 45 GAP to mimic the ballistics of 45 ACP.

Parting Shots: 45 GAP vs. 45 ACP

While the 45 GAP was intended to match the performance of the 45 ACP in a smaller package, it never really took off. That’s the significant drawback to the cartridge.

If you were keeping a tally, four sections (recoil, accuracy, stopping power, and reloading) were tied, and the 45 ACP won the remaining three sections (hunting, self-defense, and overall cost/availability).

The 45 ACP is the clear winner solely based on cost and availability, as neither cartridge offers a ballistic advantage.

Don’t pass up on the large selection, excellent prices, and incredible customer service you receive by purchasing ammo from Ammo.com!

Written by

Wes Littlefield