Comparing Handgun Calibers: Bullet Size + Performance
As a new shooter one of the more perplexing pieces is looking at all the ammo and understanding what the specs mean. There are a few rounds that users will recognize just from sheer popularity like the 9mm and 5.56. But what do the numbers actually mean, how do you read them? The basic answer is some ammo is measured in the metric system and others in the imperial system but even then the difference between two seemingly close rounds can be quite different, this isn’t shoe sizes after all. Picking your caliber is about a whole lot more than the number on the box.
Pick your caliber
Take a look at any gun shop and it is obvious there are a lot of calibers available, so how do people pick their caliber? There are several factors that go into selection, we’ll take a look at the top few that make everyone's list.The cost per round is a big factor for most people but it is one that has to be weighed with consideration of other factors and should not be the sole determining factor. Availability may also come into play depending on the market, the more popular the caliber the more is made but also the more it is in demand.
The purpose of the firearm is a top consideration. Does the round need to accomplish certain feats or is it just a range toy or perhaps it is for personal protection or a particular hunt? What you plan to use the firearm for not only impacts the selection of the firearm itself but also the caliber needed and/or wanted.
Choosing a caliber in which your skill level can still accurately deliver hits on target is another factor to consider. All the power might sound good, but if you can’t control the firearm during recoil, let alone hit where intended, it is not an option that should be at the top of the list.
For some shooters variety is the spice of life and they own a range of guns chambered in a variety of calibers, others like to keep it simple with say 9mm for pistol and 5.56 for rifle. We all have our favorites but it’s good to experience different calibers and see what it’s like to shoot them first hand.A great example for understanding that ammo calibers aren’t a linear progression are the 9mm Luger and 10mm Auto. They might be numerically close with 1mm difference in bullet diameter but the bullet weight, case length, muzzle velocity, and ft-lbs of energy are different resulting in unique firing experiences for each one.
Differences between 9mm Luger and 10mm Auto
So just how different are a 9mm Luger and 10mm Auto? Well quite a bit actually. The rounds are built with different specs which makes them ideal for different use cases.This is where it gets a bit into the weeds about ammo, while highly interesting to some, others aren’t sure exactly what it all means. We’ll take a look at some basic pieces but if the sciency part makes your eyes glaze over, think about this as a way to convey the difference between these two rounds; 10mm Auto is an appropriate round against a bear, while a 9mm Luger is more appropriate for self defense.
The Specs
As established the bullet diameter is 1mm difference, but the case length and diameter of the 10mm is a fair bit more than the 9mm. The larger case allows for more propellant and therefore fires heavier bullets at a higher muzzle velocity. This means that the felt recoil between the two rounds is noticeable as is the overall power differential.
Stopping Power
These specs add up to what we refer to as stopping power or how effective the round is at stopping the threat. Stopping power is not quantifiable in and of itself, but we can evaluate it in other ways. Due to modern innovations the 9mm and 10mm leave similar permanent wound cavities but the 10mm will hit much harder causing a larger temporary wound cavity.
Recoil
The recoil of the 10mm can be hard to manage which makes quick, accurate follow up shots harder to deliver. In fact the FBI had to move away from the 10mm as it was not a controllable round for the agents. They moved to the 9mm which has roughly half the recoil of the 10mm. The 9mm has enough stopping power for human on human engagement and allows the user to manage recoil better, shoot faster and deliver with better shot placement. In self defense we are accountable for every round and stopping the threat needs to be executed quickly, making the 9mm the more common choice. As mentioned before, if you can shoot different calibers you can start to feel just how different they are from each other.
Magazine Capacity
As shown in the specs the 10mm is just an overall larger round making the round count generally lower than with 9mm. Capacity may be more comparable with say two Glocks, the 17 holds 17+1 rounds of 9mm and the 20 holds 15+1 of 10mm so not too big a difference and can be increased with some mag extensions. In 1911’s the 9mm capacity is up to 10 while the 10mm is generally 8.The 9mm is a very popular choice but it doesn’t mean it is the only choice, the 10mm has its place and if you can control it by all means use it as you please. So when might you choose a 10mm over a 9mm and vice versa.
What’s the purpose of the firearm?
Any time you choose a firearm knowing the purpose is always going to give some direction in what features are necessary or wanted. If a range toy is the main purpose then wants may rank higher than needs, but when the firearm has a job more factors should be considered.For self-defense and concealed carry 9mm is the popular choice, the options for guns and accessories are endless, capacity is high, recoil is lower and overall they are lighter to carry and easier to shoot. While a 10mm can be carried there are some added considerations, with a major one being overpenetration. During an encounter skill drops, which means accuracy declines, so being able to control the firearm, manage recoil, and deliver quick, accurate follow up hits is critical. Does a larger caliber with higher penetration present an advantage or disadvantage for you? An individual's skill level highly impacts this but using the right amount of power rather than all the power available is something to highly consider. The 9mm has proven to perform well in human encounters.
If the gun is meant for a hunt, then the 10mm is the more popular choice. When hunting larger animals the 10mm is an adequate round, and strong recoil is less of a concern and follow up shots are not as common. The heavier bullets and higher velocity allow them to pack the necessary punch. The 10mm is a common choice for backcountry and is capable of taking down feral hogs and bears due to the overall power factor of the round allowing it to penetrate fully and reach vital organs.
The Takeaway
So what should a new shooter take away from this? First, it is obvious that a little education can go a long way so read and watch what you can so you can make an informed decision rather than assuming based on face value. Second is that the right gun is always going to be one that you can manage, even under stress, to deliver accurate hits on target.The 9mm and 10mm are not the only options for handguns either, there are plenty of others to choose from. Take some time to rent or go with a friend to experience the different calibers and see what works for you. In fact, with the Mantis X10 Elite you can use the Recoilmeter drill in live fire to see just how well you can handle the recoil of a particular round.
Once you have settled on a caliber and firearm don’t forget to get training, take class and continually practice. Using a system like Laser Academy is an easy way to get the 5 minute practice snack each day and if you settled on a 9mm and a 10mm don’t worry we have laser cartridges for each, plus other popular calibers.
Kayla House
Author