The principle of operation of the Kalashnikov assault rifle: device, circuit and technical features

Kalashnikov assault rifle (AK) is a legendary weapon that has become a symbol of reliability and simplicity. Since its inception in 1947, it has gone through hundreds of modifications, but the basic principle of operation has remained unchanged. Why AK-47 and his descendants are so popular? It's all about the brilliant engineering thought of Mikhail Timofeevich Kalashnikov, who connected gas automatic with rotating shutter - a solution that is still considered the standard for assault rifles.

In this article, we will analyze the structure of the machine gun “by the bones”: from the gas piston to the trigger mechanism. You will learn how the reload cycle occurs, why the AK so rarely misfires, and what technical tricks make it unpretentious in any conditions - from arctic frosts to sandstorms. We will also answer questions that gun owners and enthusiasts often ask: is it possible to shoot from an AK without lubrication, why does it “spit” cartridges towards the shooter, and how does the burst work?

If you have ever held a Kalashnikov assault rifle in your hands, you have probably paid attention to its characteristic sound when firing - the rhythmic “tak-tak-tak.” This is not an accident, but the result of the coordinated work of all mechanisms. Even after 70+ years of operation, the AK remains one of the most popular and copied small arms in the world. And today we will figure out why.

1. The main components of the Kalashnikov assault rifle: what's inside?

The design of the AK is built on a modular principle, where each element strictly performs its own function. The main nodes can be divided into three groups: receiver with gas engine, bolt group and trigger mechanism (trigger mechanism). Let's go over the key components:

🔹 Trunk — the heart of the machine, made of high-alloy steel by cold forging. Inside there is a rifled channel with 4 right-hand rifling (pitch 240 mm for AK-74 and 235 mm for AK-12). On the muzzle there are compensator (to reduce barrel bounce) and front sight base.

🔹 Gas chamber - a cylindrical unit under the barrel, into which powder gases enter through a hole in the barrel wall. It is here that the energy of the burning gunpowder is converted into mechanical movement of the piston.

🔹 Bolt carrier with gas piston - a moving element that transfers energy from gases to the gate. Located at the front of the frame piston, and behind - fighting ledges to interact with the shutter.

🔹 Shutter - a rotating part with 7 lugs that locks the barrel. Inside the shutter there is drummer, which hits the cartridge primer.

🔹 Return mechanism - a spring with a guide rod that returns the bolt frame to the forward position after firing.

🔹 Trigger mechanism (trigger mechanism) - a complex system of levers and springs responsible for the fire modes (single/automatic), safety and trigger release.

🔹 Butt and forearm - in classic models they were made of wood (birch, beech), in modern ones (AK-12, AK-15) - made of impact-resistant plastic. The butt is attached to the receiver and serves as a support when shooting.

🔹 Store — box-shaped, sectional, 30 rounds (standard). B AK-74 a magazine with a characteristic bend for 5.45x39 mm caliber cartridges is used.

Interesting fact: in the first prototypes AK-47 the store was straight like SVT-40, but later it was made curved for reliable supply of cartridges. This decision became the hallmark of all subsequent modifications.

2. Gas-operated automatics: how powder gases make an AK fire

The operating principle of the Kalashnikov assault rifle is based on removal of part of the powder gases through a special hole in the barrel. This is the so-called gas automatic with long piston stroke. Let's figure out how it works step by step:

1️⃣ Shot. When you press the trigger, the trigger hits the firing pin, which in turn pierces the cartridge primer. The powder charge ignites and the bullet moves down the barrel.

2️⃣ Gas removal. Part of the powder gases through gas outlet (located approximately 20 cm from the breech) falls into gas chamber. Gas pressure reaches 30–50 atmospheres.

3️⃣ Piston movement. Gases press on gas piston, which is rigidly connected to bolt carrier. The frame begins to move backwards, compressing return spring.

4️⃣ Unlocking the shutter. Via ~15 mm recoil, the bolt carrier rotates the bolt (due to the interaction figured groove and combat ledge), releasing the barrel. The cartridge case can now be removed.

5️⃣ Removing the cartridge case and feeding a new cartridge. The bolt carrier continues to move backward, removing the cartridge case ejector hooks and squeezing return spring. At the same time magazine feeder picks up the next cartridge.

6️⃣ Return to forward position. The return spring expands, pushing the bolt carrier forward. The bolt captures a new cartridge and forces it into the chamber, then turns and locks the barrel.

7️⃣ Trigger reset. At the end of the movement, the bolt frame cocks the hammer, and the machine gun is ready for the next shot.

The entire cycle takes a fraction of a second! When firing in bursts (AK-74 gives up to 600–650 rounds per minute) the process is repeated automatically until the trigger is pressed or the cartridges run out.

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Attention: In modern modifications (AK-12, AK-19) is used adjustable gas block, which allows you to configure the exhaust of gases under different conditions (pollution, use of a muffler). Classic AK-47/74s do not have this option.

3. Bolt group: why does an AK so rarely misfire?

The bolt is one of the most loaded parts of the machine gun. Used in AK rotating shutter with 7 lugs, which ensures reliable locking of the barrel. Let's figure out how it works and why the system is so resistant to pollution.

🔧 Shutter design:

• 🔘 Battle ledges — 7 pieces, engage with cutouts in the receiver, providing rigid locking.
• 🔘 Drummer - a spring-loaded rod that transfers the energy of the trigger to the cartridge primer.
• 🔘 Ejector - a hook with a spring that holds the sleeve until it is removed.
• 🔘 Reflector - a metal protrusion on the bolt frame that “throws” the cartridge case through the receiver window.

🔄 How does the shutter interact with the frame?:

When the bolt frame moves back, the bolt rotates 30° (thanks to the figured groove and the combat stop), freeing the barrel. When moving forward, the reverse process occurs: the bolt captures a cartridge from the magazine, sends it into the chamber and turns, locking the barrel.

🛡️ Misfire protection:

• 🔹 Long piston stroke — the bolt frame travels a long way, which gives time to extract the cartridge case even with high contamination.
• 🔹 Large gap between bolt and receiver — allows you to work even when exposed to sand or dirt.
• 🔹 Powerful return spring — ensures reliable chambering of the cartridge even with a weak chamber.

📊 Comparison with other systems:

Characteristics	AK (rotating bolt)	M16 (butterfly)	FN SCAR (short stroke)
Sensitivity to pollution	Low	High	Average
Design complexity	Simple	Complex (direct gas exhaust)	Average
Reliability of extraction	High	Medium (depending on lubrication)	High
Bolt group weight	~500 g	~300 g	~450 g

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Attention: Despite the legendary reliability, AK does not tolerate prolonged shooting without breaks. With an intense burst (more than 100 rounds in a row), the barrel overheats, which can lead to sticking of sleeves (when the cartridge case “sticks” to the chamber). In combat conditions, it is recommended to take pauses to cool down.

4. Trigger mechanism (trigger): how the fire switch works

The Kalashnikov assault rifle trigger is a complex system of levers, springs and sears, responsible for three key functions:

1. Pulling the trigger (firing a shot).
2. Fire mode selection (single/automatic).
3. Trigger lock (safety).

🔫 Basic elements of USM:

• 🔘 Trigger - impact element, cocked by the bolt frame.
• 🔘 Trigger - starts the firing process.
• 🔘 Single fire sear — holds the trigger after a shot in “single” mode.
• 🔘 Automatic fire sear — releases the trigger while the trigger is pressed (for a burst).
• 🔘 Translator-fuse - a lever on the right side of the receiver that blocks the trigger and selects the mode.
• 🔘 Self-timer - provides automatic fire.

🔄 How fire mode selection works:

Position fuse (upper, “P”) blocks the trigger. In position single fire (“OD”) after firing the trigger is captured by the sear and held until the trigger is released. In mode automatic fire ("AB"), the single-fire sear is disabled and the hammer is re-cocked with each reload cycle.

🎯 Setting nuances:

• 🔹B AK-47 and AKM The translator has 3 positions: safety, single, automatic.
• 🔹B AK-74 added mode fixed burst of 3 rounds (on some modifications).
• 🔹B AK-12 The trigger is completely modular - you can change fire modes without disassembling the weapon.

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Attention: When assembling the trigger after disassembling pay special attention to setting the self-timer. Incorrect assembly may result in spontaneous queue when switching from safety to single fire!

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5. Features of shooting: why the AK “spits” cartridges and how to fix it

One of the most recognizable “disadvantages” of the AK is ejection of cartridges to the right and up, which may be inconvenient for left-handers or when shooting from cover. Why does this happen and can it be changed?

🔥 Reasons for "spitting" with cartridge cases:

• 🔹 Receiver window design — it is located on the right and has an upward bevel for reliable extraction.
• 🔹 Reflector on the bolt carrier - a metal protrusion that “knocks” the sleeve to the side.
• 🔹 Weapon angle — when shooting “from hand,” the machine gun often tilts to the left, which enhances the effect.

🛠️ How to reduce shell expansion:

1. Use sleeve catcher (for example, from PKK or AK-12).
2. Install sleeve deflector (a metal plate attached to the receiver).
3. Train correct grip: The right hand should press the butt tightly to the shoulder, reducing the tilt.
4. In modern modifications (AK-12, AK-19) the receiver window is made wider, which reduces the ricochet of cartridges.

💥 Other features of shooting from an AK:

• 🔹 Barrel toss — the compensator reduces, but does not completely eliminate. B AK-74 The throw is less due to the 5.45x39 mm cartridge.
• 🔹 Recoil - y AK-47 (7.62x39 mm) stronger than AK-74, but remains manageable thanks to ergonomics.
• 🔹 Accuracy — at a distance of up to 300 m, the AK shows accuracy of ~15 cm (when firing from a rest).

Why do shell casings sometimes get stuck in the receiver window?

This happens due to:

1) Window dirt — sand, dirt or lubricant residues interfere with the free movement of the sleeve.

2) Sleeve deformation - when the barrel overheats, the sleeve swells and jams.

3) Ejector wear - if the spring is weakened, the sleeve is not removed completely.

To fix it, you need to clean the window, check the ejector and let the barrel cool.

6. Disassembly and assembly: step-by-step instructions for beginners

AK disassembly is divided into incomplete (for cleaning and lubrication) and full (for repairs). We will analyze incomplete disassembly, which every owner should be able to perform.

🔧 Procedure for partial disassembly:

1. 🔹 Separate store — press the magazine latch and remove it.
2. 🔹 Check if there is a cartridge in the chamber — move the bolt frame back and visually inspect it.
3. 🔹 Separate the cleaning rod - pull it out from under the barrel.
4. 🔹 Separate the receiver cover — press the protrusion of the guide rod of the return mechanism and remove the cover.
5. 🔹 Remove the return mechanism — lift it by the rear end and take it out.
6. 🔹 Separate the bolt carrier from the bolt — pull it back all the way and lift it, then pull it forward.
7. 🔹 Separate the bolt from the frame — turn the bolt counterclockwise and remove it.
8. 🔹 Separate the gas tube from the barrel lining — move the cover forward and remove it.

🔄 Assembly after cleaning:

Assembly is carried out in reverse order. Special attention give:

• 🔹 Correct installation return mechanism — the spring must fit into the groove of the bolt frame.
• 🔹 Fixations shutter - it should rotate freely in the frame.
• 🔹 Closing receiver covers — it should snap into place without play.

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Attention: During assembly never pull the trigger, if the bolt group is not installed! This may damage the sear or self-timer.

7. Frequent malfunctions and their elimination

Even the legendary AK is not immune from breakdowns. Let's look at the most common faults and how to fix them.

🔴 Misfires (cartridge does not ignite):

• 🔹 Reason: contamination of the firing pin, weak cartridge primer, wear of the firing pin.
• 🔹 Solution: clean the firing pin, replace cartridges, check the firing pin for wear.

🔴 The cartridge is undershot (the bolt does not reach the end):

• 🔹 Reason: chamber contamination, weak return spring, magazine deformation.
• 🔹 Solution: clean the chamber, replace the spring, check the magazine.

🔴 Automatic shooting in single fire mode:

• 🔹 Reason: wear of the sear of a single fire, incorrect assembly of the trigger.
• 🔹 Solution: replace the sear or rebuild the trigger.

🔴 Case jamming in the chamber:

• 🔹 Reason: barrel overheating, chamber contamination, low-quality cartridges.
• 🔹 Solution: Allow the barrel to cool, clean the chamber, use high-quality cartridges.

🔴 Weak extraction (the sleeve is not removed):

• 🔹 Reason: wear of the ejector, contamination of the gas chamber, weak powder gases.
• 🔹 Solution: replace the ejector, clean the gas chamber, use cartridges with a normal powder charge.

📌 Fault prevention:

• 🔹 Clean and lubricate the machine gun regularly (especially after shooting).
• 🔹 Use high-quality cartridges (avoid “homemade” or heavily contaminated ones).
• 🔹 Check the fastening of the gas tube - its backlash can disrupt the automation cycle.
• 🔹 Do not allow sand or dirt to get into the receiver.

8. FAQ: answers to popular questions about AK

❓ Is it possible to shoot an AK without lubrication?

Technically yes, but not recommended. The AK is designed to perform under extreme conditions, but lack of lubrication accelerates wear on parts (especially the bolt carrier and receiver). In the short term (for example, in combat) this is acceptable, but for long-term operation, lubrication is required.

Use special gun oils (for example, Ballistol or LPX) - they do not thicken in the cold and do not attract dirt.

❓ Why is AK-74 more accurate than AK-47?

This is due to several factors:

• 🔹 Cartridge 5.45×39 mm has less recoil and a flatter trajectory.
• 🔹 Reduced caliber reduces spread when firing in bursts.
• 🔹 Long sighting radius (y AK-74 — 378 mm versus 373 mm for AK-47).
• 🔹 Improved ergonomics (for example, the cocking handle has been moved back).

At a distance of 600 m, accuracy AK-74 1.5–2 times better than AK-47.

❓ How to distinguish AK-47 from AKM?

They are very similar in appearance, but there are key differences:

Sign	AK-47 (1947–1959)	AKM (1959–present)
Receiver material	Milled steel (heavy)	Pressed steel (500g lighter)
Compensator	Missing or simple	Improved, with side slots
Butt	Straight, birch	With a downward slope, made of beech or plastic
Rate of fire	~600 shots/min	~650 shots/min

Also AKM accuracy and reliability have been improved due to a modified trigger and gas system.

❓ How many rounds can be fired from an AK without overheating?

It depends on the conditions:

• 🔹 In battle: 30–50 rounds per burst with pauses for cooling.
• 🔹 At the shooting range: up to 100–150 rounds intermittently (10–15 shots at a time).
• 🔹 Extreme conditions (frost, mud): no more than 20–30 rounds in a row.

Signs of overheating: the barrel changes color (turns blue), the cartridges begin to stick, and accuracy drops.

❓ Is it possible to install a silencer on an AK?

Yes, but there are nuances:

• 🔹 On AK-47/74 required modification of the gas block (installation of adjustable gas exhaust), otherwise the automation will work unstably.
• 🔹 In modern modifications (AK-12, AK-19) the muffler is installed on the thread without modifications.
• 🔹Using a muffler reduces reliability due to changes in gas pressure.

In Russia, civilian silencers for AK prohibited (classified as special means for silent shooting).