What makes a gun accurate? That’s a complicated question that involves the gun itself, the ammo, and the environment. If we focus purely on the firearm, we generally want consistency. This means a good barrel with a perfectly square muzzle crown. Accuracy demands a rigid connection between the stock and bedding to prevent shift. The chamber requires tight tolerances that hold the cartridge consistently and align the bullet the same way every time.
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- Killing Accuracy – The Barrel
- Beyond Wear
- Action and Chamber
- Nuts and Bolts
- What Else?
At the end of the day, you need a mix of high-quality materials, craftsmanship, and good quality control. That’s not always easy, so we often pay top dollar to achieve it. What makes a gun inaccurate? It’s clearly a reversal of what drives accuracy, but sometimes accurate guns become a little less accurate, or a lot less accurate, regardless of ammo or environment.
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What causes that? That’s what we are going to discuss today.
Like anything man-made, barrels will degrade. Some last longer than others, and it is often dependent on how the rifle is shot, and what it’s shooting. For example, a .243 Winchester will burn out a barrel faster than a .223 Remington if all things are the same.
Rifling erosion is a big threat to your accuracy. The rifling wears down, becomes less defined, and the bullet is no longer engaging the rifling as well, which can create less consistent stabilization.
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Your muzzle crown sits at the end of your barrel, and when it’s damaged, you can see issues. As the bullet leaves the barrel, the gas follows it. As gas follows it, it engages the rifle crown, and if the rifle crown is damaged, it can create different angles of pressure on the bullet as it leaves the barrel.
One of the most common issues that’s easy to rectify is a dirty barrel. Carbon, copper, lead, and other residue build up eventually and can change how the bore and rifling engage the barrel. This can create inconsistency.
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Some things, like chrome lining, which is meant to preserve the barrel, can affect accuracy. Normally, things like chrome lining aren’t going to cause a huge effect on most rifles, but on rifles designed for extreme precision, it can be an issue.
Chrome lining isn’t plated perfectly, and there can be inconsistent layer thickness. If your barrel has any flaws, chrome lining can adhere to these imperfections and make them even worse. Again, for your average AR, this isn’t going to cause most shooters any problems, but if your rifle’s goal is to produce 0.5 MOA groups, it might create a problem.
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Barrel material can also create issues. For example, a stainless steel barrel provides greater overall accuracy than chrome-moly, since it is easy to use for precision work. Quality is still king, and a good chrome-moly will beat a bad stainless barrel.
Rifling is another accuracy factor. There are different types of rifling and different ways to create rifling in the bore. Different methods do different things and can affect accuracy, barrel durability, gas seal, and more. Most precision rifles feature 5R rifling with single-point cut rifling, and boy, do you pay for it!
A loose action and poor bedding can create consistency issues. It’s often such a minor issue that you can’t visually see it or feel it, but it can cause consistency issues. This may require the rifle to be rebedded by a skilled professional.
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Headspace is another issue. If headspace is excessive, the cartridge is going to move when the firing pin strikes the primer. This can create alignment issues, which cause accuracy issues. If the round shifts forward, it can cause inconsistent ignition. That leads to inconsistent velocity. Too much headspace can be dangerous and lead to cases rupturing and exploding.
The chamber and throat can also erode over time. The throat is going to take the brunt of the heat and pressure. Like anything, it will degrade over time, and this degrades consistency. A rough chamber or throat can impact the bullet’s surface, causing accuracy issues if it deforms the jacket.
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The bullet has to jump from the case mouth to the start of the rifling. Erosion widens and lengthens the throat, which can increase jump distance and affect consistency overall.
If you are an AR shooter, you likely know all about nuts, namely, barrel nuts. A barrel nut clamps the barrel into the receiver. If the barrel nut becomes loose or was never properly installed, you’re going to have problems. If the threads are damaged, you’re going to have problems. Namely, the barrel is not held in a consistent manner and perfectly aligned position.
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On a similar topic, anywhere the barrel connects to the receiver can be an issue. If it’s damaged or improperly machined, or if the barrel threads are inconsistent, the barrel won’t be perfectly centered.
Locking lugs are what lock the bolt into the receiver or barrel extension, depending on the firearm. As these locking lugs erode, they can get sloppy when the bolt is locked. This can create headspacing issues and action movement, which creates accuracy inconsistency.
I started this journey and consumed a lot of articles and YouTube videos trying to get down to brass tacks, but man, this is such a deep subject that I think it’s impossible to provide a short and concise list of what affects accuracy.
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Outside of people with very precise rifles and good shooting skills, most of us will only notice these problems when they are extreme. However, the most common issue is likely the sights or optics. I’ve had plenty of sights or sight mounts get a little loose and cause issues. That is, unless the shooter simply lacks skill, which I’ve also sadly experienced a fair bit.
If you’ve ever wondered why two ARs or bolt guns can have radically different prices, it’s because the higher quality control to ensure accuracy costs money. That’s just one portion of building a good gun, but an important one.
