The AK Side Rail - How It Works

Something to note is that since about 1954 the AK actually has had a factory designed method to mount optics - the side rail plate. While not standard issue on every AK it has been effective on the specialized rifles it was added to, and was eventually adopted as standard issue around 1992 in the AK74M series. Considering the AK was first deployed about 1947 you can look back and see that for about 60 of it's 65 year history in Russia the AK has had an effective way to mount optics when the mission required their use. Also of note is that during the past 20 years the ability to use optics has actually been standard right from the factory. Coincidentally you may have noticed that's about the same time frame that optics began to become more and more popular in the West as well.

Another thing to consider is that the side rail design is not an accident, it was designed for a specific purpose and it has proven itself effective for half a century or more in Russian and former Soviet service. Many countries have used the same or similar side rail mounts as a standard way to mount optics; and of course the SVD Dragunov has used it's original optic and side rail for over 40 continuous years with only minor changes during that time.

In contrast to what many believe, the Soviets and Russians continually improved equipment and gear over many decades of service, either to make things easier or cheaper to manufacture on a large scale or to improve performance and reliability. It is interesting to note that of all the things the Soviets and Russians could have chosen to do when it came to an optical solution, they elected to keep the same system in place relatively unchanged, while at the same time continually improving other systems as required. This does not mean the side rail is the perfect solution or the final answer in optics, but it should be an indication that it does work and has been battle proven in numerous conflicts.

The side mount is designed to be removed and returned without the optic losing zero and in practice if the tension is adjusted properly they will do just that and perform as expected. There are a number of clamping mechanisms for how this is accomplished but they generally work the same. They are designed to be slid on from the rear of the receiver, pushed forward and secured by the locking lever... none are designed to slide on from the front of the rail and be pushed towards the back of the receiver. The reason is because under recoil side rail mounts tend to walk forward to the front of the rifle, not backward. By design there is a stop mechanism in the clamping part of the mount...on the SVD mount it's a small bump type rivet near the front and on the AK style clamp it's built into the rear of the mount itself.

Mounting types:
We commonly refer to optics mounts as either AK or SVD type mounts but there are actually many more than that, and they are different based on manufacturer. In reality most Russian optics carry a universal AK/SVD mount as do most BelOMO optics outside the POSP series. This means that most any optic produced by either company can be fitted to SVD's or AK's using a suitable side rail. (Note that many variations exist between different countries and the rails they manufactured, in this case I am specifically referring to Russian/Belarusian designs)

When the term AK mount vs SVD mount comes into play it is usually when talking about the BelOMO POSP series, or the actual PSO-1 Dragunov optic that NPZ produced for the SVD.

One thing to note is that all optics mounts are designed to slide on the rail from the rear of the receiver and are pushed toward the front and then locked into place with the throw lever.
None of them are designed to slide on from the front.
This is because optics tend to walk forward under recoil and an optic slid on the front will eventually lose zero and possibly fall off. This happens because each mount is designed with a stopping rivet or the back of the mount that runs into part of the rail and keeps it from moving forward. When slid on from the front these parts do not connect and there is nothing to prevent the optic from moving forward if the tension from the lever loosens. It is possible to slide SVD mount optics onto AK's rails from the front but it is pure luck if nothing happens to the mount or the zero when being used this way.

SVD clamping mounts need the center groove for the stop pin to slide into and therefore SVD mounts will not fit the common AK side rail plates.
Vepr owners can rejoice knowing that almost any AK optic will fit their rifle however, because it does have the center groove

AK Pattern (Top)
Vepr (Bottom)
Vepr (Top)
SVD (Bottom)

Vepr
Universal clamping mounts will fit either style of side rail plate and the SVD rail


Clamping mechanisms simplified
There are really four main types to understand:

1: The original SVD mount (locking lever on top, lever throws and locks forward)
The stop pin to prevent the optic from walking forward is on the front of the mount



SVD mounts will not fit AK rails because the stop pin prevents it from seating on the rail. Note that the Romanian PSL is an AK pattern rifle but uses an SVD style rail.


2: The SVD style universal mount (locking lever on top, lever throws and locks rearward)
The stop pin to prevent the optic from walking forward is on the rear of the mount



3: The original NPZ and BelOMO style universal AK+SVD mount (lever on the bottom)
NPZ:

80's era NSPU night vision scope


Note that the Universal mount fits AK's and SVD's
Axion Kobra, BelOMO is the original designer of the mount


4: The civilian MTK-83 AK mount (lever on the bottom)
BelOMO makes this mount as well as the one above



RS Regulate has an incredibly well made and very light side mounting system, shown here with 1P78-1P Kashtan. This uses the castle nut method for tightening and is an AK mount. Outside of the NPZ mount this is hands down the best side rail you can buy and is readily available in the US


The primary difference between the SVD mount and the Universal types is how far forward they will seat on a rail. Remember that SVD optics sit at the front of the longer SVD rail but AK optics sit centered over the shorter AK rail.
With experience you will notice that the clamp pivot mechanism is intended to sit in the center cutout of any given side rail. By that I mean the optic must slide forward on the rail until the clamp can freely open or close and it can't do that if it's not in the correct spot on the rail, which is the center cutout.
By looking at where the clamp pivot mechanism is at you can get a pretty quick idea of what rail it was meant for because of how far or close to the back of the rail it will end up.

NOTE
To further clarify not all optics use a stop pin. Many of the universal SVD mounts have the stop pin but 'regular' AK mounts actually use the back of the clamping mechanism to prevent the optic from sliding forward. You can see some are pins and some are the mount itself.




Examples of side rail mounts using various clamps:

Top Left: BelOMO MTK-83 AK mount (this is what we typically refer to as the AK mount)
Top Right: NPZ universal AK/SVD mount

Bottom Left: Molot AK mount (similar to MTK-83)
Bottom Right: K-VAR AK mount (variation on SVD/universal type mount)

SVD mount top and middle, MTK-83 AK mount bottom:


BelOMO Universal mount (Axion Kobra is similar):

PK01-V and some of the newer BelOMO optics do not have a stop pin or flat edge on the back of the mount to keep them from sliding forward. When mounting they have to be lined up with a center cutout on the AK rail by hand or they will keep sliding forward and come right off from the front. Instead of a stop pin to prevent them from moving forward instead the mechanism is actually in the throw lever itself, when lined up with the center part of the AK rail it acts as a cam when locked and prevents the optic from moving forward.

Variety of AK specific mounts. Note that Obzor, PK-A and PK-AS use the universal style of SVD mount adapted for AK rails:


The two left optics are actual SVD mounts, the four on the right are universal SVD style mounts

Zeiss ZFK also uses a variation of the SVD mount:

Adjusting the AK/Universal type mounts:

RS Regulate has a great video

Avtomats in Action has an excellent tutorial

PSO and POSP optics can swap between SVD mounts, SVD universal style mounts and the MTK-83 mount. Simply remove the four brass screws on the side and the two on top inside and swap mounts. There are two pins that the mount is seated on and often a type of glue to help keep everything secure. A little light tapping with a rubber mallet will break the seal and allow the base to be removed. Sometimes the pins come loose, my experience is that the optic will function correctly without them.

Example of the original SVD clamp and the SVD style universal.

MTK-83 on top, SVD original on bottom

Example of Romanian LPS/TIP2 that has had the SVD base swapped with the MTK-83

Normally the LPS uses an SVD mount

Employing Optics
Chin weld vs cheekweld is a common observation when employing AK optics and is often a source of complaint from those of us used to a cheekweld and nose to charging handle type training. While I was trained the same way by Uncle Sam, in my experience the chin weld is genuinely effective when using optics on AK's and with only a little practice is very easy to get used to.

Generally speaking the former Soviets and the Russians do not consider pinpoint accuracy to be of critical importance and they do not share our Western mindset of ringing out the maximum possible accuracy of a given rifle's design. Instead they rely on a philosophy that is rooted in many years of experience dating back to World War 2 and has worked for them for many decades. I generally refer to as combat accuracy and by that I mean the intent is to score hits on a man size target at accepted battlefield engagement distances quickly, with multiple shots and against moving targets in a dynamic battle. 

In my experience and in researching AK's in combat,  the AK74 and associated optics do perform very well and do perform as intended. The design philosophy is based around effective speed and accuracy rather than ultimate accuracy, with the understanding that in a combat situation the rifleman may not have the luxury of taking a perfect shot every time. Like many things I have learned over the years about the former Soviets and the Russians, it's the tried and true methods rooted in history that tend to be the basis of designs and doctrine, and optics appear to follow in stride.

Remember that these days the Russian military primarily uses the AK74, they do not use the AKM as a general rule and have not for almost 40 years. Times have changed...while we might still tend to think of AK's as being inherently inaccurate and being poor choices for optics, in reality that is a perception that we in the West seem to be relatively unique in having. In Russia the mindset is very different because the AK74 is actually very different than the AKM and most of the modern optics in Russia have been designed for the AK74.
For most of us the AK74 is just an AK47 that fires a smaller bullet, but there is actually quite a bit of engineering in the design... while similar, the AK74 is subtly different in ways that make all the difference. Longer ranged, more accurate, faster followup shots and better performance on full auto especially at longer ranges are the result of these subtle differences. This is also not an accident, the AK74 is the result of calculated engineering intended to produce a specific result and it appears to have achieved those results based on it's 40 year history and combat experience.

When you add in optics designed especially for the AK74 you see a very different picture than you do of the original AK47 that we are most familiar with, but we still often continue to see the AK74 through this older view point.

Range Finders
Many Russian and former Soviet optics have a range finder built into the reticule. Originally the military range finder was based on a 1.7m tall target (about 5 feet 5 inches) and civilian versions of the POSP used the non military 1.5m scale, but later both military and civilian optics used 1.5m as the standard. Hunting versions of the POSP use a 1.0m scale for game, while 1P78 Kashtan uses the mils reference system.


PSO-1 uses the 1.7m range finder

1P29 is 100% military issue but has the 1.5m range finder

To use these style of range finders bracket the target in between the smallest number that it will fit. The number it matches is the distance in 100's of meters.