The Firearm Guide: How to do a Functions Check on a Firearm

"What is a functions check?"

Well, a functions check is exactly how it sounds - it checks the functions of your firearm! But I'm sure you want to know what that means, so we'll dive into exactly what a functions check is and how it's done for most of your firearms.

Before we begin, I need you to understand that there's two types of firing mechanisms I'll reference. One is striker-fired, and one is hammer-fired. Take a few minutes and learn about them real quick. Otherwise, you might get confused at some explanations.

Skip ahead by clicking on one of these relevant sections!

Functions Check: Handguns (Strike-fired)

Functions Check: Handguns (Hammer-fired)

Functions Check: Rifles/Firearms with multiple firing modes

A functions check ensures that each of your firing modes on your firearm works properly. This includes your safety as well.

You want to conduct this check any time you disassemble and reassemble your firearm, regardless of the reason. This makes sure you did it properly and nothing broke in the process.

Again, it's not to insult your intelligence, but it's a good habit - especially if someone else dissembled it and reassembled it for you.

While firearms are all different, they generally all function the same way. Like I've described, albeit very simply in other posts, the trigger simply acts as the mechanism to activate a firing pin or hammer that causes your gun to fire.

Each firing mode acts a certain way to get different results, for example automatic firing is different to semi-automatic firing. Functions checks ensures that these modes continue to act the way they're supposed to, and generally this involves seeing how the firing pin/hammer acts when pressing and releasing the trigger mechanism.

This will make sense once I explain the process. Lets go ahead and dive into it.

Functions Check: Handguns (Striker-fired)

Most modern, striker-fired firearms are going to operate the same when it comes to conducting your functions check. And, just to verify it for the 100th time, I tried it on both my P365X and Beretta APX, and yep, it works the same regardless.

Step 1: Clear your firearm and ensure it's on safe.

You'll be squeezing the trigger and pulling the slide back on this in order to get it to 'fire' - so make sure you don't actually punch a hole through anything.

But you already did this when you picked it up - right?

You can use an empty magazine for this as well to confirm that your slide will stay back once the magazine is empty, but after you confirm that I would just put the magazine away.

Step 2: Point it in a safe direction, pull the slide back all the way then release

Essentially your goal here is to prepare the weapon to fire by resetting the striker. We're about to check and make sure that the firearm is doing this properly.

Step 3: Attempt to fire by squeezing the trigger while it is on safe (if applicable).

First we're testing to ensure your safety works properly. You shouldn't be able to squeeze the trigger back, and you shouldn't hear any clicking noises that insinuate the striker has been activated. Give it some good squeezes to confirm.

If you don't hear anything: Good! Move on.

If you do hear something: Stop! If you're mechanically inclined, I'd look into the trigger and safety mechanism and see where the issue lies. Or, you can find a gun shop nearby to take a look at it. Do not operate your firearm with a broken safety.

Some firearms don't have a manual safety. If not, then move on.

Step 4: Click off the safety and put your handgun into fire mode.

We're getting ready to test and make sure it does what it's supposed too!

Step 5: Squeeze the trigger - and continue squeezing it.

You should hear and slightly feel a 'click' - this is the striker activating. Thankfully, it won't put a hole in anything because you diligently ensured it was clear.

If you don't hear anything, check whether or not you assembled your firearm correctly or have it looked at by a gunsmith. I know on M17's if you don't place the slide back correctly it can cause an issue with the trigger not working, even though it feels normal to squeeze.

Ensure you continue squeezing the trigger for the next step.

Step 6: With the trigger still squeezed, pull the slide back once more and release.

This is going to prep the striker again. You're basically just manually conducting what happens when you fire the handgun for real.

Step 7: Release the trigger

You should hear a 'click' - this is the trigger mechanism being reset in line with the firing pin.

Again, if you don't hear anything - try it through once more and double check your assembly.

Step 8: Squeeze the trigger again

You should once again hear the 'click' of the striker activating. All we're doing here is confirming that the striker did in fact reset and allowed you to fire once again.

And that's it! Your handgun works fine. Not too bad huh? So, to reiterate:

Step 1: Clear your firearm and ensure it's on safe.

Step 2: Point it in a safe direction, pull the slide back all the way then release

Step 3: Attempt to fire by squeezing the trigger while it is on safe (if applicable).

Step 4: Click off the safety and put your handgun into fire mode.

Step 5: Squeeze the trigger - and hold it back. (Click!)

Step 6: With the trigger still squeezed, pull the slide back once more and release.

Step 7: Release the trigger (Click!)

Step 8: Squeeze the trigger again to confirm (Click!)

Functions Check: Handguns (Hammer-fired)

Some of the actions are similar to striker-fired firearms, so I'll omit anything I don't need to re-explain.

Step 1: Clear your firearm and ensure it's on safe.

Step 2: Point it in a safe direction, pull the slide back all the way back then release the slide forward.

Your hammer should be cocked fully back.

Step 3: Attempt to fire by squeezing the trigger while it is on safe.

You'll generally see the firing pin block move near the rear of the handgun. Just pull the trigger a bunch if it allows and check out the small moving piece. The hammer itself should not move though.

Step 4: Click off the safety and put your handgun into fire mode.

Step 5: Squeeze the trigger slightly, but not all the way.

You should be able to move the hammer slightly. This is checking your double action.

Step 6: Squeeze the trigger completely, and hold it.

The hammer should fall forward.

Step 7: With the trigger still squeezed, pull the slide back once more and release.

The hammer should fall back again.

Step 8: Release the trigger

You should hear a click, but the hammer should not fall forward.

Step 9: Squeeze the trigger

This step checks your single-action. It should be a very easy squeeze, and the hammer should fall forward.

Function check complete!

Now lets try out something with a multiple firing modes.

Like above, a lot of these steps will be similar, so I'm not going to re-explain anything that I feel I don't need too.

Functions Check: Rifles/ Firearms with more than one firing mode

Step 1: Clear your firearm and ensure it's on safe.

Step 2: Point it in a safe direction, pull the charging handle back all the way then release

Step 3: Attempt to fire by squeezing the trigger while it is on safe (if applicable).

Step 4: Click off the safety and put your weapon into 'Semi' (if applicable)

Step 5: Squeeze the trigger - and hold it back.

You should hear a click. This is the hammer falling.

Step 6: With the trigger still squeezed, pull the charging handle back once more and release.

Step 7: Release the trigger

You should hear a click. This is the hammer resetting into place.

Step 8: Rotate the selector switch to 'burst' or 'auto' (if applicable)

Step 9: Pull the charging handle back all the way then release

Step 10: Squeeze the trigger - and hold it back.

You should hear a click. This is the hammer falling.

Step 11: With the trigger still squeezed, pull the charging handle back once more and release.

Step 12: Release the trigger

You should not hear a click. Pull back the charging handle to reset it.

Interesting, right?

For an automatic rifle there are two methods to activating the hammer.

The first method, which parallels most any semi-automatic rifle, has what's called a disconnector that is in charge of holding the hammer down during the re-cocking process, where the bolt retracts back and then forward again. After that happens and the trigger is released, the "click" you hear is the disconnector releasing the hammer back into place to be activated again via the trigger mechanism.

The second method, for automatic firing capability, uses what's called a SEAR. Unlike in semi-automatic firing where the disconnector holds the hammer and the trigger activates it again, the SEAR is in charge of both actions. It holds down the hammer during the re-cocking process, and then when the bolt rides forward again it hit the SEAR, releasing the hammer into the firing pin again. This makes it completely independent of the trigger.

So, the reason you don't have that second "click" is because the trigger is locked into place to allow the SEAR to operate as intended.

Neato.

So basically all you're doing for a functions check is manually conducting the actions taken when the firearm actually fires. That's it. It's simple once you understand that, and you'll be able to work just about any firearm.

As always, stick around and check out our other guides for more knowledge!