shooters corner

concerns with the SKS Carbine

concerns with the SKS Carbine

* First is the possibility of a "slamfire," or worse the ignition of a round out of battery.
* The second being accidental discharge due to poor hammer/sear engagement.

A "slamfire" is essentially an unintentional and uncontrollable discharge of more than one round. It may be 2 of 3 rounds being fired instantaneously, or the complete emptying of the magazine. It is usually caused by a seized firing pin--due to debris, powder residue, cosmoline, or a host of other substances. It can also be caused by using commercial ammunition with soft primers. This is dangerous because it can happen unexpectedly and without warning. Yourself or others could be harmed, or worse.

The SKS Carbine features a "free-Floating" firing pin which means it has no spring to return and hold the pin rear-ward in the bolt. Since the firing pin can freely "rattle" inside the bolt body, extra care must be taken to ensure the firing pin channel remains clean. If the firing pin becomes stuck in a protruded manner, and bolt is closed, the pin will strike the primer and ignite the round. It is also possible that the first round will not be ignited until the trigger is pulled, which will then jam the firing pin forward to the protruded postition, triggering the involuntary ingition of some or all remaining rounds.

Since the SKS Carbine is a semi-automatic firearm, it will reload instantly after the first round is fired. If the firing pin remains stuck in the forward position, primers will continue to be struck involuntarily (without using the trigger) until all remaining live rounds are fired. It is easy to see why this is an unsafe condition.
The easiest way to remedy this problem is to assure your bolt is clean of any and all residue. This can be done by many methods. Complete dis-assembly, inspection, and cleaning is my preferred method.

It is my recommendation that the bolt be completely disassembled and the firing pin channel be cleaned thoroughly (I find myself using pipe cleaners and non-chlorinated brake cleaner). Soaking the bolt assembly is not sufficient enough to clean out hardened, sticky cosmoline and other foreign debris. I also discourage oiling the pin, as oils will only attract dirt and other residues eventually seizing the pin (and that is what you're trying to avoid!!!).

For a detailed technical artical on how to dis-assemble your bolt, visit's article on Bolt Disassembly/Reassembly

A few side notes:

* Though firing pin orientation doesn't typically matter, in some Chinese variants the firing pin can be replaced upside-down in the bolt body, jamming it in the protruded postition. It might not be a bad idea to mark your firing pin's orientation with the body before your remove in from the bolt.
* Ben Murray makes a retro-fit kit that replaces your firing pin, with a new pin and spring. This will virtually elimitate the possibilitly of a "slamfire" all-together. For more info check out Ben Murray's website.

Hammer/Sear Engagement
This section will discuss the trigger group, with emphasis on the hammer and sear.

There are 3 types of Hammer/Sear Engagement. They are:

* Negative Engagement - As the trigger is slowly pulled, the hammer moves forward slowly before breaking and contacting the firing pin.
* Neutral Engagement - As the trigger is slowly pulled, the hammer remains neutral and does not move before breaking and contacting the firing pin.
* Positive Engagement - As the trigger is slowly pulled, the hammer moves rearward slowly before breaking and contacting the firing pin.

Of the three types of hammer/sear engagement, the positive type is the safest and most desirable.

To check your SKS, pull your bolt back to cock the hammer, then remove your receiver cover and recoil spring. Take care not to let the recoil spring shoot across the room! You can now look down to see your hammer. Slowly squeeze the trigger while watching the movement of the hammer. You may have to repeat several times, as the movement can and will be minimal. (Keep your fingers clear).

Why is hammer/sear engagement so important?

The safety mechanism on the SKS simply acts as "doorstop" to the trigger. It does not disconnect the sear, or cease function of the hammer. Instead, it simply keeps the trigger from moving rearward. If the rifle is cocked and loaded, and is knocked, dropped, bumped, or the likewise the sear can still move and the hammer can still drop. This is especially the case with a negative hammer/sear engagement.

The best way to describe how this could happen is to use an analogy.
Let's say your car is dangling on the edge of a cliff, ready to fall hundreds of feet to the bottom of a canyon. (This is the hammer in the cocked position.)

* If a bird lands on the hood of your car, which is over the edge of the cliff, your car will teeter and fall into the canyon. (This is negative engagement as your SKS is accidentally bumped)
* If you remain motionless in your car, as it teeters on the edge, you will most likely just remain there staring out the windshield at your possible demise. (This is neutral engagement)
* If a tow-truck happens by and hooks up to the rear bumper of your car, pulling you away from the edge of the cliff, you will be saved from catastrophe. (This is positive sear engagement)

But that doesn't make sense! How does it work?

When the hammer is in the cocked (rearward) position, it's edge is resting on the sear. If you have a negative hammer/sear engagement, the sear actually slopes downward toward the edge where the hammer releases. If the SKS is jarred or bumped, the hammer can, under the tension of the hammer spring, slip down that slope to the end of the sear and release firing the chambered round!

How do you correct this?

Positive hammer/sear engagement! If the sear slopes in the opposite direction as it does in a negative engagement situation, if the SKS is bumped or jarred the hammer is forced away from the face of the sear and the hammer cannot possibly be released!

My recommendation is: If you have a negative or even a neutral hammer/sear engagement, GET IT FIXED!!!
I will cover a do-it-yourself method further down in this article.
In the mean time take extreme caution while handling. Take special care not to bump or jar the firearm, as this could accidentally set the hammer free.

Addressing the SKS Trigger

The SKS Carbine trigger, in general, is made to have a lot of trigger creep. If your SKS is like most, there is some slack in the trigger. Once you get past the slack, the second stage of the trigger is fairly rough and heavy. In most cases the "creep" experienced in the second stage is quite lengthy.

What is the reason for this long pull 2-stage trigger? It is most likely a safety concern. It is not uncommon to have new military recruits that have little or no firearms experience. It is safer to give them a weapon with a long trigger pull with a lot of slack over one with a "hair-trigger." There is a lesser chance of accidental discharge by a jumpy cadet in a stressful situation. This becomes especially critical when the user is running/jumping/diving around in the mud, concentrating on everything else but his weapon. The extra creep helps to assure the SKS only fires when the user means for it to fire.

The creep also acts as a cushion for poor hammer/sear engagement. In most cases this large cushion of creep will help keep the hammer from releasing if bumped or jarred no matter how poor your hammer/sear engagement is. I still recommend you remedy neutral and/or negative engagement as it is still possible for the hammer to accidentally release.

My first SKS had negative hammer/sear engagement. As a test, I cocked the hammer and bumped the unloaded firearm firmly on the ground 3-4 times. "CLICK!" the hammer struck. The test was repeated with the same results. Imagine if the firearm were loaded. A bump against a tree, accidentally dropping it, tripping on a root...all of these situations could be potentially lethal with the unsafe firearm.

The SKS trigger is fairly complex in design, so If you don't feel comfortable taking it apart or making any modifications then please don't! If you would like to reduce the creep in your trigger, smooth out much of the roughness, lighten your pull, and remedy your hammer/ sear engagement problems, visit Kivaari's Little Armory for an SKS Target/Match Safety Trigger Job. He comes highly recommended, has a quick turn around, and will leave you in awe. You will shoot better, and more happily!

If you would like to learn a little more about how the trigger works, and possibly make your trigger function a little better on your own, please read on!