How to Check AR15 Headspace without Gauges

How to check ar15 headspace without gauges? We know that AR15 Headspace in a sniper rifle refers to the chamber cartridge measurement. The measurement begins from the shoulder because it has a predetermined distance from the face to the bolt.

And the headspace is the measurement of the minimum size a chamber for a round to rest in before being fired, despite all the grime or debris inside this chamber. The headspace basically measures how suitable the chamber can be for firing.

Checking headspaces on an AR15 is an important task. It prevents any firing failures or other accidents from happening. And it’s common to do headspace checking with gauges. It may be a bit tricky doing it without the gauges. But with the proper instructions and tools, you may learn how to check AR15 headspace without gauges.

Steps to Check AR15 Headspace without Gauges

Usually, headspaces are checked with gauges. In general, there are 3 basic gauges to use. They are the GO gauge, the NO-GO gauge, and the field gauge. But in case you don’t have such gauges, you’ll have to follow the alternative of checking without a gauge.

And because of the risk, you may not want to do it yourself. In that case, you can try going to stores and have someone measure the headspace for you.
But if you do plan on doing it yourself, we can follow the below steps to check firearm headspaces without the help of gauges:

Check here AR-15 Rifles Buying Guide and Full Reviews to buy.

Removing AR15 Headspace

Remove the extractor from the bolt-on your firearm.


Get a brass piece and a flush timer. Make sure there’s no ammo or gunpowder in the cartridge. Place the piece inside the chamber and then proceed to insert the bolt.

Adding Tapes

Add lots of cellophane tape, scotch tape, or any other type of masking tape to it, so that the layers of tape prevent the bolt from coming off. Resistance should be felt around 1/8 inches to ¼ inches before it’s fully closed.

Sliding the Firing Pin

By the back of the bolt, slide a firing pin in a way that it touches the brass. Here the firing pin is used as a headspace tolerance of the chamber. Then the plunger pushes the brass forward into the shoulder, leaving headspace at the bolt’s face.

Keeping Focus

Keep focused and notice if there is any difference between bolt face, including the brass, and the firing pin flush.
The gap may seem minimal, but that very gap will be the headspace. Even if the gap is small, your firearm’s headspace is still considered well constructed. If there’s no gap, then you have too much headspace.

Other Methods to Check AR15 Headspace without Gauges

Other Methods to Check AR15 Headspace without Gauges

Below are the other methods to check AR15 headspace:

Using Calipers

Here you would be using calipers to measure headspace. It might be a tougher technique since measurements may not be accurate. But it’s cheaper since everyone has calipers in their collection of tools.

First, you’d need to mark the shoulder with a marker and then measure all sides of the cartridge since calipers won’t measure that accurately. After measuring and finding out the dimensions, you can clearly compare the difference or gap and find out the headspace.

The advantage of marking the shoulder on your cartridge helps you determine headspace since you’ll see where it ends up in your chamber.

Using Factory Cartridge Round

All you need to do is take a factory cartridge round, fire it, and then measure it. Compare it with the minimum and maximum headspace it should have. If it’s over the maximum amount, then you’ll need to try different bolt heads and experiment until the headspace is just about right.

Final Words

There are various ways to check headspace. But if you really want to check headspace on a bolt action of a rifle without the use of gauges, then the above steps and methods should be followed.

Despite the risk, those are still simple steps to help you measure headspace quickly. And this method also saves you from having to buy expensive gauges. Hopefully, you can maintain checking AR15 headspace without gauges without any issues.