How To Check AR 15 Headspace Without Gauges?

The AR-15 is an excellent rifle for home defense, hunting, and target shooting. But You might not even be sure how much headspace your rifle has or where your barrel should be set. You need to order special tools to measure headspace, which takes time and patience. Fortunately, there is a simple way to check headspace on any AR-15 without buying expensive gauges.

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One of the most important things to check on any rifle before firing is how far back the bolt should stop when you pull it back and how it feels when you push it forward with your fingers over the ejection port. If either one of these measurements is off, that could indicate a problem with headspace. A headspace gauge can be expensive, but if you don’t want to buy one, there are other ways to determine if your rifle has this issue. 

In this blog post, we will teach you how to check AR 15 headspace without gauges?

A word of caution

If you doubt whether your gun has been damaged, then don’t do this, but if you want more information on how to check AR 15 headspace without gauges, we recommend reading our blog post.

What Is Headspace? The Significance Of Headspace

How To Check AR 15 Headspace Without Gauges?

A rifle needs good headspace for safety. Too little or too much of either will create problems like getting jammed up and exploding on us while shooting. So the question arises what a headspace is in the first instance?

“Headspace is how far the cartridge (bullet) fits into the chamber.”

In other words;

“Headspace refers to how much space there is between an opened cartridge case and its chamber in a firearm’s barrel.”

Guns with too much headspace can be dangerous because the bullet might get stuck in the barrel. If you have too little, there may not be enough pressure behind that round to make it go off when we want it to do – this could lead to an explosion or malfunctioning of a firearm during use.

List Of Tools You’ll Need To Measure Properly

So, how do you check your AR-15 headspace without gauges? There are a few ways to measure the space between the bolt and chamber end of an AR rifle. Here is the list of tools you need to acquire for measuring the headspace of your AR rifle.

How To Check AR 15 Headspace Without Gauges?

  1. Measuring calipers ( a digital, vernier-type is recommended)
  2. Ammo casing (empty). Either brass or steel ammo will work, but we prefer to save the brass ones 
  3. Trigger pin/rod assembly from a firearm has been stripped down such that the trigger pin and rod should be visible.
  4. Ruler or tape measure (metric if possible) – for measuring how far you are pushing the bolt carrier back into the receiver
  5. A small screwdriver to disconnect your firing pin from its spring 

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Guide: How To Check AR 15 Headspace Without Gauges

The first step is identifying how far back you are putting your bolt carrier into the receiver. This measurement will dictate how much firing pin protrusion you’ll see if there’s a problem with head spacing.

You can use either a ruler or tape measure and simply line it up with the face of the bolt carrier where it enters inside the receiver on one side and make sure that at least half an inch sticks out from this point towards you when looking through the ejection port. If not, remove some spacers from behind by loosening them with a ratchet and socket, then tighten them back up.

The second step is how far the bolt carrier moves when you let go of it to trip the sear on an empty chamber with the rifle cocked (you can use your finger or cocking handle). You don’t need any ammunition for this part, as long as there’s no magazine in place.

It should move about halfway forward before being tripped by contact from the trigger bar; if not, that means things are too tight and need some loosening/moving around with spacers again until it does.

If it goes farther than halfway, either loosen or remove one spacer at a time to see how much difference that makes–if still more than halfway after removing one spacer, the problem is how far back the hammer hooks are and how much they’re lifting.

The third and last step is to put a snap cap in place of an empty magazine, cock the rifle–with no ammunition in it. Pull the trigger until it trips (you’ll hear ‘click’). The bolt carrier should not go past that point; if it does, you need more spacers or have something too loose.

Why It Is Important To Check Headspace? Problems That May Occur Due To Inaccurate Headspace

Since headspace is how much distance there is between the cartridge and the chamber of a firearm, it becomes essential to ensure that your bolts close on the right amount of clearance. If you have too little or too much space, then one or more things will happen:

1: A Bulged Case 

The brass will swell towards one end like an egg. This indicates that there was insufficient (or no) clearance between the bolt face and cartridge rim at some point in time during firing because of excessive headspace; this condition typically occurs when attempting to fire rounds with cases shorter than the recommended minimum length.

2: Infrequent Firing: 

The bolt may not be able to slam into the battery (or closed position) because it needs more room to go in. This can create an unsafe condition for both shooters and those around them since most guns need their bolts moving back and forth with some force to work correctly.

3:Inaccurate Shots/Bad Accuracy:

Springs are meant to push cartridges forward, so they pop up out of magazines smoothly, but if there’s no room for them to do so, they may not load properly (or at all) or cause a jam. This can make shooting less accurate and even create dangerous conditions where parts get stuck in the barrel of your AR-15, making it unusable.

How To Check AR 15 Headspace Without Gauges?

4:Gun Damage: 

The bolt slamming against springs with too much force will eventually wear down other mechanical components, creating more friction that may come into contact with areas like triggers, bolts, and inside one’s magazine well. All this added force can damage one’s gun over time requiring repairs and replacements that cost money.


The most common cause of injury is ammunition that does not feed properly through the chamber. Suppose there isn’t enough punch from each round’s firing pin strike on top of the cartridge, for instance (due to insufficient blowback). In that case, this leads to light primer strikes, which often result in jams, hammer follows failures, and other malfunctions with ever-increasing frequency until one day.

Many gun enthusiasts and hunters are interested in how long an AR-15 will last. Contrary to popular belief, the average lifespan of an AR-15 is 20,000 rounds before it becomes irreparably damaged or jammed. Don’t be fooled by its lightweight aluminum receiver—the reinforced polymer lowers can withstand a lot more than you might expect.

The headspace of your rifle must be in-between two points. If it is below the minimum, then the rounds will get stuck when fired. If it goes above the maximum, then unspent ammunition can come out after firing because there is not enough room before the round snaps back into its case. The range for tolerable variation between those two points is a variation of 6 thousandths of an inch or 0.006 inches and not more than this.

If the rifle is new, you should check for headspace before firing it. If the rifle is old and has a very high round count, you may not need to check for headspace. You should consult your manufacturer’s instructions as they change how often or if you need to check AR-15 headspace with gauges regularly.


At the end of the blog post, We are glad you’ve made it to this point in our article. The headspace is an integral part of any rifle, and without knowing how to use a gauge correctly, you may be risking damage or injury. Fortunately for you, we have provided some tips on how to check your AR-15 chamber with no gauges required. It’s worth noting that these methods will only work if your barrel has not been changed and still retains its original dimensions. If this does not apply to you, then please consult a gunsmith before proceeding. 

Happy hunting.

Author Profile

Gabriel Tackett
Double major in Engineering and Geology at the University of Minnesota. Experienced shooter & hunter for over 15 years. Certified NRA officer for over 10 years working as a writer at .

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