How to Measure a Gun Barrel For a Holster

Measure a Gun Barrel For a Holster

Ah, the holster. The right-hand man to your concealed carry weapon. If you’re looking for information on rifles, this isn’t the right place. Today, we will be focusing on pistols and holsters. Finding the perfect fit holster is just as important as finding the perfect pistol; they work hand in hand with each other. A lot of gun owners struggle to find a holster fit that gives good concealment and still functions well as a carry holster. Why is that?

One word: measuring. What’s the most important part of your firearm? You might think of the caliber, trigger guard, or even a spare magazine. But most gun owners would probably say the barrel. Which, I would have to agree with. The barrel is what aims and shoots your firearm, and is essentially what the weapon revolves around to make it work.

Gun holsters are usually tailored to specific handguns, meaning that the measurements are mind with a certain type of weapon in mind for that particular holster. That way, if you buy the right holster set, you’ll get the perfect fit every time. But, in order to do that, you’ll need to measure the main component of your handgun: the barrel.


Why Does Barrel Length Matter?

Handguns are often sorted by their size. Different barrel lengths will matter when it comes to performance, holstering, and even competitive shooting. Different barrels, like a threaded barrel, can also contribute to different barrel lengths. The length can also dictate what the weapon is intended to be used for, whether that’s for official law enforcement or just for the average concealed carry permit. Concealment is also a major factor that can be affected by the barrel dimensions. Holster accessories can vary depending on the size, which can affect what you may have to purchase in order to properly conceal your weapon when needed.


Since the gun barrel is such a large component, it often has a great influence on the total weight of your pistol. A barrel that is excessive in length can result in a handgun that is forward heavy, meaning that it tends to try and tip forward when you are aiming. This can make it difficult to maintain an accurate aim when you’re trying to fight the sheer weight of your weapon.

Also, a semi automatic pistol will usually have a longer slide, which is attached to the top of the barrel. The longer the barrel the longer the slide. This of course, will add even more to the weapon’s weight since the slide is another crucial part of the gun.


Most gun owners don’t have a fully decked-out, military style pistol. So, chances are, you’re just using the plain old iron sights. Which is great, but can also be affected by the barrel length. When using your iron sights, there’s a certain amount of distance between the front and rear sights depending on the barrel size. The longer this distance is, the greater chance of deflection, which is basically just deviation from your perfect alignment. So, the longer the barrel, the greater chance you have of being more inaccurate with your iron sights.


This is the most important point of today’s discussion. Concealed carry. When measuring your barrel for a holster, you’ll want the most concealment as possible, hence the “concealed carry.” The barrel of the gun is the part that goes and sits inside the holster, so that is the main part that you’ll be aiming to hide.

This is why it’s so important to measure your barrel. If your barrel is super long, you might have a harder time trying to conceal it than a shorter barrel, so you might have to compensate for that when you go to purchase your holster. If you have a shorter barrel, your handgun will be more easily concealed. Either way, knowing the exact length of your barrel is important for a perfect fit and a good concealment job.


This goes along with the concealment category. While you want to conceal your weapon, that also means that you should be able to carry it comfortably in the style that you choose. A long and heavy barrel will add more weight, and will therefore make it less comfortable and easy to carry. If you’re using a waistband holster, it can drag your belt or pants down. With an ankle holster, it can be very difficult to walk with. This is why most experienced concealed carry gun owners go for a pocket pistol or a carry gun, which is much smaller and lighter and made specifically for this reason.

Measuring Your Barrel

Measuring your barrel sounds pretty easy, right? I mean, yes, but it’s also very important that you do it exactly right in order to get the best holster fit. A lot of people might refer to their gun manual, which is a great idea, but might not be accessible for everyone. So, if you can’t read the product description, learning how to measure your own barrel is a good skill to have. So, let’s break down the steps you can take to get a perfect fit for your holster.

Use a Ruler or Tape Measure

The first and probably most obvious way to measure the weapon is with a ruler or a tape measure. Now, this sounds simple, but there’s specific spots that you’ll need to measure from in order to get the right holster size.

For a typical pistol, you’ll want to measure between the muzzle and the back of the chamber. Where you’ll be measuring will depend on the type of gun that you have. For a revolver, you’ll measure between the muzzle and the back of the forcing cone.

While this method is the most familiar and simple, it’s not the most recommended just because it’s not the most accurate. There’s related products out there that are made specifically for barrel measuring that you might want to take a look at before you settle on just one measurement.

Use a Caliper

A specifically designed tool is a caliper. A caliper is a measuring device that is designed to take the diameter and size of the inside and outside of the barrel. This method is much more accurate and reliable than just using a tape measure. If you can get your hands on one, I would definitely recommend it.

First, place the caliper around the outside of the barrel. Tighten it so that it fits nicely around the weapon and take the measurement of the caliper. Then, repeat for the other side of the barrel. Once you have the 2 measurements, average them together and you have your barrel size. This method is much more accurate and is backed by experienced gun owners and groups like the ATF.

Use a Dowel Rod

This is by far the best and most accurate measuring method you can do. A measuring rod or a dowel rod will be inserted into the barrel of your gun and that is what will be used to give you the most precise barrel measurement. However, you can only use this tool on handguns that have an integrated chamber, like a semi automatic pistol. Weapons like a revolver, that have an open chamber, will not need a measuring rod.

To use this, insert the dowel rod into your barrel. The rod must be smaller than the diameter of the barrel. Make sure the slide is closed when you insert the dowel rod. Push the rod down until it touches the breech face of your weapon. This is the recommended distance from the ATF to measure your barrel from.

Using a marker, mark down the end of the muzzle on the rod and pull it out. Now, you have the dowel rod with a mark on it to indicate exactly how long your barrel is. This method is relatively easy and gives a very accurate (and the ATF’s approval) measurement.

For a revolver, this won’t be necessary. Simply take your ruler or measuring tape and measure from the end of the muzzle to the beginning of the cylinder chamber. This will give you an accurate measurement.

Brand Recommendations

There’s plenty of types of holsters that you can buy: a leather holster, an IWB holster (inside waistband), OWB holster (outside waistband), and even a kydex holster. Leather holsters are probably the most common or well-known. All these types of holsters will depend on your preferences, waist size, and even budget. If you’re looking to carry easily, there’s some pistol brands that you should keep in mind too. If your current weapon is too bulky, you might want to take a look at these brands so you can purchase a pocket pistol or something that might be easier for your personal carrying needs.

Smith & Wesson

Smith & Wesson is a top pistol brand that offers many weapons and other products for you to choose from. The SW MP Shield is a top notch pistol and one that a lot of gun owners favor. This brand is very reputable and is a great place to start, especially if you already have an MP Shield.

Dan Wesson

This is another great firearm brand. If you’re looking to get a custom pistol that you can create to fit perfectly in your holster, Dan Wesson is the brand for you. They offer a ton of customization options for you when it comes to buying a pistol, which will grant you the better chance of getting a good carry pistol that will fit comfortably in a holster.


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