9mm VS 45: What Is The Difference Between The Two?

9mm vs 45 Ammo Comparisons


Choosing your gun is amongst one of the most crucial decisions you make in your life. Usually, depending upon the intended purpose of the weapon, common considerations that guide a gun buying decision include its size, shooting range, ease of firing, sound produced on firing, weight and the cost. For instance, if you need the gun for your safety and protection at home, then you might be okay with a big gun like a shotgun or a rifle as long as it comfortable to fire. If you intend to carry the firearm on your person then you would want it to be compact and easy to conceal.

However, another important factor that can influence your decision is the kind of cartridge the gun uses and what will you need. There are many different kinds of ammo. So many that a first-time buyer can get thoroughly confused. For the sake of dialing down the confusion, we are only going to pitt a 9mm vs 45 in this article.

 

What Is A Cartridge?

Commonly confused with a bullet, a cartridge or ammo actually has these components:

  • A bullet which is the actual part of the cartridge that impacts the target.
  • A casing which holds the primer and powder and makes the shell of the cartridge.
  • A primer which helps ignite the powder.
  • A powder that explodes.

At the bottom of the cartridge is the primer. It is a chemical compound which is struck by the firing pin at the base of the cartridge when the gun’s trigger is pulled. This creates a spark and ignites the powder. The powder catches fire and explodes. This explosion creates a large amount of pressure that throws the bullet out of the cartridge and ultimately out of the barrel of the gun resulting in the weapon firing.

The empty cartridge needs to be removed from the weapon to make room for the next cartridge to be fired. Some weapons do this automatically while some need to be emptied manually.

 

How Does Ammo Differ?

gun ammo


If it is your first experience with owning a gun, the sea of options in ammo can make it very difficult to choose the right ammo for you. But there are two broad differences that can help you out.

The first is whether you want a rimfire or a centerfire ammo. In the centerfire cartridges, you’ll be able to see the primer in the center of the base of the bullet. If the base of the cartridges is flat with no primer in the center, it is a rimfire ammo.

It just means that firing pin will hit the center in the case of centerfire ammo and it will hit the rim in case of the rimfire ammo. Though, the rimfire bullets are much cheaper, you will usually find them only small caliber.

This brings us to the second big difference - the size of the ammo. There are many different sizes of cartridges - 9mm, .40 S&W, 45 ACP, 12 Ga, .50 BMG and the list goes on.

 

Why Size Matters

Ammo contributes significantly to the choice of gun you make because of its size. Guns that use larger cartridges have more stopping power - that means a greater impact on the target. At the same time, they are slow to fire continuously because of the higher recoil. Their size may also decrease the magazine capacity, which we will talk about later, and their follow up shots are also limited.

Guns with smaller cartridges offer the advantage of fast follow up shots and more room for multiple shots. Also, their stopping power is less, which is safer for first time users.

As promised, let us understand and compare the 9mm and 45 to help you understand which one is the cartridge for you so you can choose the right gun for yourself.

 

History

Both, the 9mm and 45 go back to the beginning of the 20th century.

Actually named the 9x19 Parabellum, the 9mm was designed by George Luger way back in 1901 and went into production a year later. It was adopted by the German Navy and German Army in the years 1904 and 1906, respectively. It was also used by the German forces in World War 1.

In the year 1904, John Browning developed the .45, commonly called the 45. Many countries including the United States used it during the World War 1.

Both cartridges have been popular amongst the worlds’ armed forces since then.

This is pretty much where the similarities between the two cartridges end. Both are so popular with patrons rooting for them equally that besides a few common factors it is always the 9mm vs 45.

 

9mm vs 45 man firing a gun


9mm VS 45: What’s The Difference?

Let’s get to the why these cartridges are so different.

Origin

The 45 was made in the United States of America while the 9mm was made in Germany.

Diameters

  • Bullet Diameter: The bullet diameter, also known as the caliber, determines the whole it makes in the target. The 9mm as the name suggests has a diameter of 9.01 mm whereas the .45 has a diameter of .452 inches or 11.01 mm. You will often find guns being named in a caliber. That is because of the diameter of the gun’s barrel and hence, of the cartridge.
  • Base Diameter: The 9mm has a base diameter of 9.93 mm, while the 45 has one of 12.1 mm.
  • Neck Diameter: The 9mm has a base diameter of 9.96 mm, while the 45 has one of 12.2 mm.

Case Type

There have been no significant findings to prove the effect of casing design on a bullet’s velocity or ballistics. Yet, some manufactures claim that their design makes a difference. In case of the 9mm, you’ll find the casing to be tapered while the 45 has a straight one.

Case Length

The case length can affect how far inside a bullet is seated in the cartridge.

You will find a case length of .898 inches in a 45 and of .754 inches in a 9mm cartridge.

Expansion

The 9mm expands .36” to .72” while the 45 expands .45” to .79”.

Length Of The Cartridge

A cartridge length should be able to accomodate the following:

  • The neck should be long enough to give the cartridge a comfortable seating and enough hold.
  • The cartridge should not be too big for the gun’s magazine.

The 9mm ammo is 19.15mm long while the 45 is 32.4mm long.

Pressure

The pressure is one of the contributors to how far and how fast the bullet is projected from the cartridge and gun. The 9mm has a maximum pressure of 34,084 psi, while the 45 has maximum pressure of  21,000 psi.

Velocity

A high speed cartridge is always better. Hence, with a velocity range of 95-1400 FPS, the 9mm beats the 45 which travels in a range of 700-1150 FPS.

Energy

The 9mm carries an energy of 115 grains: 323 foot-pounds which is much lower than the 185 grains: 411 foot pounds of the 45.

Momentum

Ballistic experts have maintained that the momentum is a good measure of the bullet’s performance. In that case the 9mm falls short of momentum by a large gap against the 45.

Primer

The 45 uses the same primer as large rifles while the 9mm uses the Berdan or Boxer primer for small pistols. The Berdan primer is mostly used by militaries though it is reusable, it is a difficult process as the primer cup is attached to the casing itself. While the boxer primer is most popular is the United States due to its ease of replacement.

Penetration

The deeper a bullet penetrates, the more damage it causes to the target. The 45 gives a bullet penetration of 11.3” to 14.3” as compared to the 9mm’s 8” to 15.9” penetration.

Capacity Of The Magazine

The 9mm cartridges are smaller than the 45. Hence, magazines can hold more of the 9mm. However, the capacity may vary depending upon which gun is being used. Usually, a magazine shipped from the factory can carry 6-14 cartridges in case of 45s and 6-20 cartridges in case of the 9mms.

Recoil

man pointing a gun

Recoil refers to the force with which a firearm recoils when it is fired without support from behind. It impacts the user and can even cause serious injury. The 9mm cartridge has a lower recoil than the 45 ammo. The latter is known to push the firearm user’s hands backward on firing.

Cost

A 9mm cartridge is much cheaper than the 45.

Happy Choosing

There you are! Now you know pretty much everything you need to know to choose the right cartridge for you. The 9mm trumps the 45 in aspects such as cost, easy to replace primer, more magazine capacity and lower recoil, the 45 seems to be made to get the job done with its higher penetration, momentum and energy.

You can now weigh the pros and cons of both the cartridges to decide what works best for you.

 

Sources:

Diffen

Pew Pew Tactical

Gun Digest

Hunter Ed

Mass Reloading

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