The Pencil Test

Imagine you're looking at a used pistol with an intent to purchase it. If it has been well used, chances are that some parts may be worn out or broken. One part, in particular, is the firing pin, which may be broken, bent, blunted etc. Another part of interest is the mainspring, which may have lost some of its strength. Or perhaps you stripped your pistol in order to clean it, and you aren't sure if you put it back together properly. There is a simple test to verify that the firing pin and mainspring are working satisfactorily and this test is the pencil test, which we will study about today. The only tool you'll need to conduct this test is a pencil with an eraser tip on one end:

A standard #2 size pencil. Click on the image to enlarge. Public domain image.

1. First, make sure the pistol is empty.
2. Cock the pistol, making sure that it is still empty.
3. Insert a pencil with the eraser end first into the barrel and push it as far as it will go (do not force it, just push it in gently). For best results, use a new wooden pencil (such as a standard #2 size pencil, like the one pictured above), with the eraser in good condition
4. Hold the pistol vertically, with the barrel end aimed upwards.
5. Make sure that the pistol is indeed empty, then pull the trigger.
6. If the firing pin and mainspring are working correctly, the pencil will move noticeably. In many pistols models, the pencil will actually come shooting out of the barrel. If the pencil doesn't move, or only moves weakly, there may be a problem with the firing pin or mainspring.

This test works on various pistol models, both hammer-fired and striker-fired types. Of course, the distance that it comes shooting out of the barrel depends on the model of pistol and also the wear and tear of the parts. For 1911 pistols in good condition, the pencil should come flying out and go at least a few feet up in the air. Glock pistols will also propel the pencil out a good amount of distance, but generally not as far as a 1911. Of course, the test also depends on the shape of the firing pin and the hardness of the eraser. For instance, in some models of M&P pistols, the firing pin may pierce the eraser instead of shooting it up. In such cases, if the pencil is put in with the unsharpened end in first, it may come flying out better. Alternatively, a plastic ballpoint pen, such as a Bic, may be used. In general, hammer fired pistols tend to propel the pencil out farther than striker fired models.

For pistols that are equipped with decocking levers (such as Sig Sauer, Ruger P95, Beretta M9 etc.), a similar test may be used to ensure that the decocking safety mechanism is working properly. As before, the pistol is cocked and the pencil is pushed in as before and the pistol is held vertically. Then, instead of pulling the trigger, the decocking lever is pushed instead. If the decocker is working correctly, the pencil should not move at all. If it moves, that means the decocker is not working properly and the firing pin is contacting the eraser.

Now on to some videos, so that you can see what it looks like.

The first video is from user Sadie Thorne on youtube and shows a quick test with a 1911 type pistol.

This video comes with no explanation, but shows the test very nicely. Notice how far the pencil comes flying out of the barrel, when the trigger is pulled.

The next video is by stdlfr11 and shows the same test done using a CZ-75 pistol.

This video has the user giving an explanation of the test, as it is being done. Note that while the pencil moves noticeably, it doesn't move as far as the one in the previous video. The reason for this becomes clear when the user pulls the pencil out as you can clearly see the indentation that the firing pin made on the eraser, which could explain why it didn't fly out as much. If the eraser had been harder or if the user had put the pencil in with the unsharpened end first, it would probably have flown out of the barrel much better. The test does show that the firing pin is functional and is not broken.

So there you have it, a simple test using a pencil ensures that the firing pin and mainspring are working satisfactorily.

Safety Mechanisms: Decocking Lever

In this post, we will study a safety feature that is present in some semi-automatic pistols that are Double Action. Recall in our discussion about revolvers that double action firearms are generally able to operate in double action as well as single action mode (unless they are labelled DAO - Double Action Only, in which case they only operate in double action mode). In pistols of this sort, the user may manually pull back the hammer to cock it and then pull the trigger to release it (single action mode), or simply pull the trigger back, which cocks the hammer and then releases it (double action mode).

When fired in double action mode, the trigger pull is harder and longer since the trigger action needs to cock the hammer before releasing it.

In many cases, people like to carry their pistols with one round chambered, but the hammer decocked and any other safety devices may be turned on or off. The pistol is "considered safe" because it takes a longer and stronger trigger pull to cock and release the hammer, than if the hammer was cocked already and the trigger merely releases it.

So when a user wants to carry a pistol in this state, they initially insert a loaded magazine normally and then pull back on the pistol's slide to load the first round in the chamber. However, this same action also cocks the hammer. So, now the user wants to decock the hammer without firing the pistol. In olden days, the trick was to hold the hammer's spur down with the thumb and then pull on the trigger and then slowly let down the hammer so that it falls back to the "safe" position without discharging the loaded cartridge. Of course, this approach has some danger in that if the user's thumb slips off the hammer's spur, it could cause the hammer to strike the cartridge with force and discharge it. In order to reduce this danger, a decocking lever was introduced.

With a decocking lever, the mechanism either blocks the hammer from slamming on the firing mechanism, or by covering or retracting the firing pin out of the way, so that the hammer can be safely released without triggering the firearm. Of course, all mechanisms can fail, so it is still a good idea to point the firearm in a safe direction before operating the decocker lever.

Decocking mechanisms are found on pistols from many manufacturers: Heckler & Koch, the Sig Sauer pistol family, Walther pistols etc.