Tag Archives: AK-74

The Engineering History of the Not So Lowly AK-47 Rivet

I’ve been involved with AK rifle building since 2006 and there’s something we take for granted – how rivets are used to secure the forged trunnions, and trigger guards to the sheet metal receiver. Not to mention the center support and side mount scope rail. Some have asked why rivets were even used thinking they were some low-end choice. The truth is quite different. Let’s move ahead and take a deeper focused look at the engineering behind the use of the rivet in the AKM rifle – it wasn’t a lowly choice by any means.

Section 1: Introduction to the AKM Stamped Receiver and Rivet-Based Assembly

The design of the 7.62mm AKM represents a pivotal moment in 20th-century small arms manufacturing. Its departure from the milled-receiver construction of its predecessor, the AK-47, in favor of a stamped-steel receiver assembly, necessitated a comprehensive and robust method for joining dissimilar components under significant operational stress. This report provides a detailed engineering analysis of the riveting system employed in the AKM, examining the materials, dimensions, geometry, and underlying mechanical principles that make it a successful and enduring design.

1.1 The Evolution from Milled to Stamped: Engineering and Production Imperatives

The original AK-47, while exceptionally reliable, was built upon a receiver machined from a solid forging of steel. This process was labor-intensive, time-consuming, and resulted in significant material waste. The primary engineering driver for the development of the AKM, introduced in 1959, was the optimization for mass production.1 Soviet engineers sought to reduce manufacturing complexity, cost, and the overall weight of the rifle without compromising the platform’s legendary reliability.2

The solution was a paradigm shift from a milled receiver to one formed from a single 1.0 mm thick sheet of steel.1 This change dramatically reduced machine time and cost, allowing for faster production rates to meet the vast needs of the Soviet military and its allies. However, this created a new engineering challenge: a thin, U-shaped stamped steel shell lacks the inherent strength and rigidity to contain the forces of a firing 7.62x39mm cartridge and guide the bolt carrier group with the necessary precision.4 The AKM’s riveting system is the critical design element that solves this problem. The following table summarizes the four AK-47 types:

Type DesignationWeapon ModelReceiver ConstructionDescription
Type 1Early AK-47 (1948–51)StampedFirst design; lightweight stamped sheet metal with riveted trunnions. Abandoned due to reliability and tooling issues.
Type 2AK-47 (1952–53)MilledFirst successful milled version; added a rear socket for the stock and heavier construction.
Type 3AK-47 (1954–59)MilledRefined milled design with lighter weight and simplified manufacturing over Type 2. Most common milled AK-47.
Type 4AKM (from 1959 onward)StampedStandardized modern AKM receiver; made from stamped sheet metal with riveted trunnions, very lightweight and economical.

1.2 The Functional Role of Trunnions and Rivets in the AKM Design

The AKM design cleverly separates the functions of pressure containment and component housing. The immense stress of firing is handled by two key high-strength components: the front and rear trunnions.6

  • The Front Trunnion: This is a precisely machined block of steel that serves as the heart of the rifle. It holds the barrel, provides the locking recesses for the bolt’s rotating lugs, and contains the peak chamber pressure upon firing. It absorbs the primary rearward thrust of the cartridge case.5
  • The Rear Trunnion: This machined steel block provides the mounting point for the buttstock and serves as the rear stop for the recoiling bolt carrier group, absorbing its kinetic energy at the end of each cycle.1

The thin stamped receiver acts as a chassis, holding these trunnions and the fire control group in their correct spatial relationship. The rivets are the non-detachable fasteners that permanently join the high-strength trunnions to the receiver shell, transferring the operational loads and creating a unified, rigid structure from otherwise disparate parts.1 Alternative methods like screwing are unsuitable due to the risk of loosening under intense vibration, while welding could warp the thin receiver and create brittle heat-affected zones.7 Riveting provides a permanent, vibration-resistant, and mechanically sound solution.

1.3 System Overview: Mapping the Primary Rivet Groups

The rivet pattern on an AKM is not arbitrary; it is a carefully laid out system designed to secure components and reinforce the receiver. The primary rivet groups, which will be analyzed in detail in subsequent sections, are as follows 8:

  • Front Trunnion Rivets: A group of six rivets securing the front trunnion to the forward section of the receiver.
  • Rear Trunnion Rivets: Two long rivets (for a standard fixed stock) that pass through the receiver and the rear trunnion block.
  • Trigger Guard Rivets: A group of five rivets that attach the trigger guard assembly to the bottom of the receiver.
  • Center Support Rivet: A single rivet and internal sleeve located midway down the receiver that prevents the receiver walls and guide rails from flexing.

The precise placement of these rivets is critical to the firearm’s function and is standardized across Warsaw Pact production, as can be seen in various build templates and diagrams.10

Top: AKMS (older-style wood handguard typical of AK-47 fitted) with type IV receiver; bottom: AK-47 with type II receiver. Image Source: Wikimedia.

Section 2: A Typology of AKM Rivets: Form, Dimensions, and Location

The rivet set used in an AKM is not a homogenous collection of fasteners. It is a specific kit of components where the geometry and dimensions of each rivet type are engineered for its designated location and mechanical function.

2.1 Rivet Geometry: A Detailed Taxonomy

The rivets used in a standard AKM can be classified into several distinct geometric types, each with a specific purpose.

2.1.1 The Swell Neck Rivet

This is the most specialized and structurally critical rivet in the AKM design. Its geometry features a standard domed head, a shank of a specific diameter, and a distinctive conical flare, or “swell,” located directly beneath the head.9 This swell is designed to fit into a corresponding dimpled (countersunk) hole in the receiver sheet. This interface creates a mechanical interlock that provides superior resistance to shear forces, a concept that will be analyzed in detail in Section 4. These are used in the highest-stress locations, such as the trunnion attachments.8

2.1.2 The Domed (Universal) Head Rivet

This is a standard solid rivet with a semi-spherical head, often referred to as a universal or round head type.15 These are used in locations where the specialized shear-resisting properties of the swell neck are not required, but a secure clamping force is still necessary, such as the upper front trunnion holes and parts of the trigger guard assembly.9

2.1.3 The Flat Head Rivet

The center support rivet is unique in that it features a very low-profile, flat manufactured head.8 This is a design constraint dictated by clearance requirements. The bolt carrier group reciprocates along guide rails inside the receiver, and a standard domed rivet head in this location would interfere with its movement. The flat head ensures a smooth, unobstructed path for the carrier.18

2.2 Rivet Specifications by Location

The following table synthesizes data from military specifications, gunsmithing resources, and commercial rivet sets to provide a comprehensive reference for the dimensions and types of rivets used in a standard fixed-stock AKM. All imperial measurements have been converted to metric for engineering consistency.

Table 2.1: AKM Rivet Dimensional and Type Specification

Rivet LocationQuantityRivet Type/ShapeShank Ø (mm)Shank Length (mm)Factory Head Ø (mm)Factory Head Height (mm)Required Receiver Hole Ø (mm)
Front Trunnion, Lower2Swell Neck, Domed Head4.09.5~7.1~2.14.0
Front Trunnion, Middle2Swell Neck, Domed Head4.09.5~7.1~2.14.0
Front Trunnion, Upper2Standard, Domed Head4.09.5~7.1~2.14.0
Rear Trunnion, Long2Swell Neck, Domed Head4.8~50.8~7.4~2.84.8
Trigger Guard, Front4Standard, Domed Head4.09.5~6.9~2.14.0
Trigger Guard, Rear1Standard, Domed Head4.07.9~6.9~2.14.0
Center Support1Standard, Flat Head4.0Varies~7.0Low Profile4.0

Data compiled and converted from sources.9 Dimensions are nominal and may exhibit minor variations based on country of origin and production year. Shank length for the center support rivet varies with the sleeve used. Rear trigger guard rivet length can vary depending on the use of a reinforcement plate.17

2.3 Analysis of National and Historical Variations

While the core Soviet design established the standard, minor variations in rivet specifications and patterns exist among different national producers of the AKM and its derivatives.

One of the most well-documented distinctions is in the front trunnion rivet pattern. Soviet/Warsaw Pact AKMs (Russian, Polish, Romanian, etc.) feature a parallel vertical alignment of the three rivets on each side of the trunnion. In contrast, many Chinese Type 56 rifles utilize a staggered or triangular rivet pattern for the front trunnion.12

Furthermore, small dimensional differences in the rivets themselves have been observed. For example, measurements of demilled kits have shown that Romanian factory-formed rivet heads for the trigger guard average around 6.9 mm – 7.2 mm in diameter, while Chinese examples can be slightly larger, averaging around 7.4 mm in diameter with a greater head height.15 These differences, while minor, reflect distinct manufacturing practices and tooling but do not alter the fundamental engineering principles of the riveting system.

Section 3: Metallurgy and Material Science of Soviet-Era Rivets

The choice of material for the AKM’s rivets is a critical aspect of its design, reflecting a deliberate balance between manufacturability, strength, and cost. The material must be soft enough to be formed without fracture, yet strong enough in its final state to withstand the violent operational stresses of the firearm.

3.1 Material Composition: Analysis of GOST Standard Low-Carbon Steels

Based on an analysis of Soviet-era general-purpose fastener standards, such as GOST 10299-80, the rivets used in the AKM are made from a low-carbon, unalloyed, quality structural steel.20 These steels are not high-performance alloys but are cost-effective, readily available, and possess the specific mechanical properties required for cold-forming applications. The two most probable grades are

Сталь 10 (Steel 10) and Сталь 20 (Steel 20).20 The number in the designation indicates the average carbon content in hundredths of a percent (i.e., 0.10% for Steel 10, 0.20% for Steel 20).22

Table 3.1: Nominal Chemical Composition of Soviet Rivet Steels (GOST 1050)

ElementSymbolSteel 10 (% Content)Steel 20 (% Content)
CarbonC0.07 – 0.140.17 – 0.24
ManganeseMn0.35 – 0.650.35 – 0.65
SiliconSi0.17 – 0.370.17 – 0.37
PhosphorusP≤ 0.035≤ 0.035
SulfurS≤ 0.040≤ 0.040
ChromiumCr≤ 0.15≤ 0.25
NickelNi≤ 0.25≤ 0.30
CopperCu≤ 0.25≤ 0.30
IronFeBalanceBalance

Data compiled from sources.22

3.2 Mechanical Properties: The Engineering Balance of Malleability and Strength

The selection of low-carbon steel is a masterstroke of process-integrated engineering. The material’s properties are ideally suited for both the installation process and the final application.

  • Malleability and Ductility: The extremely low carbon content makes these steels very soft and ductile in their annealed (as-supplied) state. For Steel 10, the hardness is approximately 143 HB, and for Steel 20, it is around 163 HB.22 This high ductility allows the rivet’s shank to be cold-formed (upset) into the buck-tail or formed head with a press, flowing to fill the hole completely without cracking.25 A harder, higher-carbon steel would be too brittle for this process.
  • Work Hardening and Final Strength: While the rivets are initially soft, the process of cold-forming induces significant work hardening (also known as strain hardening). As the steel is plastically deformed, dislocations are generated and rearranged within its crystal structure, which impedes further deformation. This has the effect of increasing the material’s tensile strength and hardness in its final, installed state. The rivet becomes substantially stronger than it was before installation. This elegant mechanism means that the assembly process itself is the final step in achieving the required mechanical properties, eliminating the need for a separate, costly heat treatment cycle for the millions of rivets produced.

3.3 Heat Treatment and Surface Finishing

It is critical to distinguish between the treatment of the rivets and the treatment of the receiver. The rivets themselves are not heat-treated after installation.27 Their final strength is a product of material selection and work hardening.

In contrast, the 1.0 mm stamped receiver is selectively heat-treated. Specifically, the areas around the fire control group (hammer and trigger) pin holes and the tip of the integral ejector are hardened to prevent wear and elongation under repeated stress.4 A common specification for this spot-hardening is a Rockwell C hardness of 38-40.13 Attempting to use a non-heat-treated receiver will result in rapid failure, as the pin holes will stretch and deform, leading to malfunction.13

The standard finish applied to military-issue rivets is a black oxide coating.9 This is a conversion coating that provides mild corrosion resistance and a durable, non-reflective black finish that matches the rest of the firearm.

Section 4: Engineering Rationale and Stress Distribution Analysis

The AKM’s riveting system is more than a simple collection of fasteners; it is an integrated system designed to manage and distribute the complex forces generated during the firing cycle. Understanding this system requires analyzing the stresses on the primary components and the specific design features created to handle them.

4.1 The Trunnions as Primary Load-Bearing Structures

As established, the trunnions are the true load-bearing elements of the AKM.

  • Front Trunnion Stress: The front trunnion bears the highest peak stress in the system. When a cartridge is fired, the expanding gases exert a force on the bolt face, which is transmitted directly to the locking lugs on the front trunnion. This force is on the order of thousands of pounds, corresponding to chamber pressures that can reach approximately 45,000 psi for the 7.62x39mm cartridge.5 The integrity of the trunnion’s locking lugs is paramount. This is why properly forged and heat-treated trunnions are essential; failures of substandard cast trunnions often manifest as cracks or complete shearing of the locking lugs.5
  • Rear Trunnion Stress: The rear trunnion experiences a different type of load: a high-energy impact. At the end of its rearward travel, the entire mass of the bolt carrier group (approximately 500 grams) slams into the front face of the rear trunnion. While the peak force is lower than the chamber pressure, it is a significant, repetitive shock load that must be absorbed and transferred into the receiver shell without causing deformation or failure.7 This repeated impact is why the rear trunnion rivets are often described as taking the most “abuse” in the system.7

4.2 Analysis of Forces: Shear Stress on Trunnion Rivets

The primary force that the trunnion rivets must resist is shear. The rearward thrust on the front trunnion and the impact on the rear trunnion create forces that try to slide the trunnions relative to the receiver skin. The rivets act as pins, resisting this shearing motion. The load is distributed among the rivets in a group, with each rivet carrying a fraction of the total shear force.

4.3 The Swell Neck/Dimple Interface: A Design Solution for Maximizing Shear Resistance

The most ingenious feature of the AKM’s riveting system is the use of swell neck rivets in conjunction with dimpled receiver holes. This is a specific design solution to the problem of transferring high shear loads into a thin (1.0 mm) sheet of metal.

In a standard rivet joint, the shear load is borne by the bearing surface of the hole against the rivet shank. In a 1.0 mm receiver, this bearing area is minuscule, making the hole highly susceptible to elongation or “egging” under load, which would lead to a loose trunnion and catastrophic failure.

The swell neck/dimple system fundamentally changes this dynamic. The process involves using a specialized die to press a conical countersink, or “dimple,” into the receiver hole.8 The front or rear trunnion must be in place behind the receiver to support the sheet during this process.8 When the swell neck rivet is installed, its conical swell nests perfectly into this dimple.13

The basic formula for shear stress (τ) is τ = F/A, where F is the applied force and A is the area over which the force is acting. This formula calculates the average shear stress across the area. 

Explanation:

Shear Stress (τ): It’s a measure of the force acting parallel to the surface area of a material, causing it to deform or potentially fail by sliding or shearing. 
Force (F): This is the component of the force that is parallel to the surface area. 
Area (A): This is the cross-sectional area of the material that the force is acting upon. It’s the area of the surface where the force is applied, not the total surface area of the object. 

So, as the area increases, the sheer stress decreases all things being equal.

This creates a mechanical interlock. The shear load is no longer concentrated on the thin edge of the hole. Instead, it is distributed across the entire conical surface area of the dimple. This vastly increases the bearing surface, dramatically reduces the bearing stress on the receiver material, and effectively locks the trunnion and receiver together, preventing any relative movement.6 Gunsmithing guides explicitly warn against trying to achieve a flush fit by removing material from the receiver instead of dimpling; doing so defeats the entire purpose of the design, leaving only the rivet’s core to resist shear and guaranteeing eventual failure.6 This feature is the key to making a thin stamped receiver perform as if it were much thicker and stronger at these critical junctions.

4.4 The Role of the Center Support and Trigger Guard Rivets in Receiver Rigidity

While the trunnion rivets handle the primary firing loads, the other rivet groups serve a crucial structural reinforcement role, stiffening the inherently flexible U-shaped receiver.

  • Center Support: The center support consists of a rivet passing through a steel sleeve that bridges the two sides of the receiver.8 This assembly acts as a critical cross-member. It prevents the long, unsupported upper guide rails from flexing inward under the lateral forces exerted by the reciprocating bolt carrier, ensuring smooth and reliable cycling. It also prevents the receiver walls themselves from bowing or pinching.33
  • Trigger Guard Assembly: The trigger guard is not merely a safety feature. When its five rivets are properly installed, the entire stamped steel trigger guard assembly acts as a structural floor plate for the receiver.34 This significantly increases the torsional and latitudinal rigidity of the large magazine well opening, preventing the “U” from spreading or twisting under load.

Together, these rivet groups transform the flexible stamped receiver shell into a strong, cohesive chassis capable of withstanding the rigors of military service.

Section 5: The Riveting Process: A Technical Guide to Proper Formation

Achieving the designed strength of the AKM’s riveted joints is entirely dependent on the correct installation process. This is a precision manufacturing operation that requires specialized tooling and meticulous adherence to procedure. Using improper methods, such as a hammer and a simple punch, will result in substandard joints that compromise the safety and reliability of the firearm.

5.1 Essential Tooling: Jigs, Presses, and Forming Dies

Modern, correct riveting practice relies on a set of specialized tools to ensure control and repeatability.

  • Hydraulic Press: A shop press, typically with a capacity of 12 tons or more, provides the slow, controlled, and immense force needed to properly form the rivets without impact shock.13
  • Riveting Jig: A purpose-built jig, such as those made by AK-Builder or Toth Tool, is essential. These jigs securely hold the receiver and trunnion assembly, ensuring it is square to the press ram. They have recesses to support the manufactured head of the rivet, preventing it from being flattened, and they align the forming tool perfectly coaxial with the rivet shank.8 Different jigs or configurations are used for short trunnion rivets, long rear trunnion rivets, and the trigger guard.33
  • Forming Dies and Tools: A set of hardened steel forming tools is used to shape the rivet. This includes cupped support dies for the manufactured head and various forming punches to create a correctly shaped, domed buck-tail on the other end.16

5.2 Receiver and Component Preparation

Proper preparation of the components is as important as the riveting itself.

  • Hole Location and Drilling: Rivet holes must be precisely located on the receiver blank. This is typically done using a plastic layout guide and a transfer punch to mark the hole centers.10 The holes are then drilled to the correct diameter (e.g., 4.0 mm for a 4.0 mm rivet) using a drill press and high-quality drill bits.37 An undersized hole will prevent the rivet from seating, while an oversized hole will result in a weak joint.
  • Deburring: After drilling, all holes must be carefully deburred on both sides. Any burrs or sharp edges will prevent the rivet from sitting flush against the receiver and trunnion, creating gaps that compromise the joint’s integrity.6
  • Dimpling: For all swell neck rivet locations, the receiver holes must be dimpled. This is done using a specialized dimple die in the hydraulic press, with the trunnion installed in the receiver to provide backing support. This forms the conical seat that the rivet’s swell neck will engage.8

5.3 Step-by-Step Installation Protocol

The general sequence for riveting an AKM receiver is as follows, using the appropriate jigs and press tools for each step 8:

  1. Trigger Guard Riveting: The trigger guard assembly is typically installed first, often with a dedicated jig. The four front rivets and the single rear rivet are pressed to secure the guard and magazine catch assembly.13
  2. Front Trunnion Riveting: The front trunnion is placed in the receiver, and the six short rivets are installed. Care must be taken to use swell neck rivets in the four lower and middle holes (which should be dimpled) and standard domed rivets in the two upper holes.8
  3. Rear Trunnion Riveting: The rear trunnion is installed using the two long rivets. This requires a specialized long-rivet jig to support the receiver and apply force linearly down the long shank of the rivet.8
  4. Center Support Installation: The center support sleeve is inserted, and the special flat-headed rivet is pressed into place, again using the long-rivet tool.8

5.4 Inspection and Verification of a Correctly Formed Rivet

A properly formed rivet must meet specific visual and mechanical criteria.

  • Visual Inspection: The manufactured head must be perfectly flush against the receiver surface with no visible gaps. A common field test is to hold the receiver up to a bright light source to check for light passing under the rivet head.39 The formed head (the buck-tail) must be symmetrical, well-rounded with a dome shape similar to the manufactured head, and centered on the rivet’s shank. It should not be flattened, cracked, or off-center.40
  • Mechanical Integrity: The finished rivet must be completely tight. There should be absolutely no detectable movement between the trunnion and the receiver when force is applied. The entire assembly should feel and behave as a single, monolithic component. A loose rivet is a failed rivet and must be drilled out and replaced.
This is a Romanian Pistol Mitralieră model 1963/1965 (abbreviated PM md. 63 or simply md. 63) and is the Patriotic Guard or ‘Gardă’ version readily identifiable by the “G” on the rear sight block. Image source: Author.

Section 6: Conclusion: The Engineering Elegance of the AKM Riveting System

6.1 Synthesis of Findings: A Robust System for a Stamped Platform

The comprehensive analysis of the AKM’s riveting system reveals a design that is far more sophisticated than its rugged appearance suggests. The transition from the milled AK-47 to the stamped AKM was a manufacturing revolution, and the riveting system is the lynchpin of its success. The key findings of this report can be synthesized as follows:

  • A Purpose-Engineered System: The AKM’s riveting system is a holistic solution to the engineering challenges posed by a thin, stamped-steel receiver. It successfully mates high-strength, load-bearing trunnions to a lightweight chassis, creating a firearm that is both durable and easy to mass-produce.
  • Specialized Components: The system does not rely on generic fasteners. It employs a heterogeneous set of rivets, each with a specific geometry (swell neck, domed head, flat head) and dimension precisely tailored to the mechanical requirements and spatial constraints of its location.
  • Optimized Material Science: The choice of low-carbon steel (such as Soviet Steel 10 or 20) is a deliberate act of engineering efficiency. The material’s initial ductility facilitates easy cold-forming, while the installation process itself induces work-hardening, providing the final required strength without the need for a separate heat-treatment process.
  • Advanced Structural Mechanics: The strength of the system is derived not merely from the clamping force of the rivets but from advanced mechanical principles. The swell neck/dimple interface is a brilliant solution for managing shear stress, while the center support and trigger guard rivets act as integral structural reinforcements, adding critical rigidity to the receiver.
  • Process-Dependent Integrity: The design’s success is inextricably linked to the correct installation methodology. Proper riveting is a precision process that requires specialized tooling and meticulous preparation. Deviations from this process directly compromise the mechanical integrity and safety of the firearm.

6.2 Final Assessment

The riveting system of the AKM is a testament to the Soviet design philosophy of elegant simplicity. It achieves maximum functional robustness with a minimum of manufacturing complexity and cost. By understanding the interplay between the stamped receiver, the machined trunnions, and the specialized rivets that join them, one can appreciate the AKM not just as a firearm, but as a masterclass in pragmatic and effective mechanical engineering. It is a system where every component, every dimension, and every step in the assembly process has a clear and logical purpose, resulting in one of the most successful and widely produced firearm designs in history.

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Are You Looking For A Lubricant That Performs Better Than CLP? Check Out Kentuckiana Gun Works – Enhanced Reliability Oil

So I stopped in to talk to Scott Igert, my good friend who owns Michigan Gun Exchange, a few weeks back. Scott told me about a new gun oil that he had samples of that the maker had handed him directly and that I ought to take a look at it. I kind of groaned because everyone and their brother claims to have the best gun oil. Some have ok oil and some don’t (remember the canola oil mess some years back?) but nobody has THE best oil.

Many times the oils they are selling you are an existing product that has been put into tiny containers with some really splashy marketing and packaging. For example, if you find a red colored weapon oil that feels, smells and is colored red like ATF, then it is probably some variant of automatic transmission fluid – Dexron, ATF, etc. If it’s colored blue and smells and feels like hydraulic fluid then that might well be what it is. Now I am not saying all products are that way but a lot are.

So, somewhat warily, I took the sample bottle home with me. It had to wait a bit until I could get around to focusing on it. The product is “Enhanced Reliability Oil” From Kentuckiana Gun Works (KGW).

In looking at the oil, it was yellow-ish with a hint of red. It’s a blend of something – but not something right out of a bottle. I felt it and it had a nice 30 weight-ish feel to it. It wasn’t really thin but it was slippery.

The smell was that of a petroleum oil but nothing uniquely stood out.

Did I taste it … no, I have standards to uphold at least while I am sober.

Okay, those quick observations may sound ridiculous to you – well, the taste part was a joke – but many products you can kind of group by color, feel and smell. This one I couldn’t because the color was unique plus it felt like a decent lubricant so I decided to dig a bit more.

I took a few drops of some common lubricants and put them on a piece of white printer paper. Left is the KGW product, then Super Lube, them CLP, followed by Mobile 1 5w-30 synthetic engine oil and finally Pennzoil Platinum Full Synthetic 5w-30. Super lube is clear – it just turned the paper black. KGW has a slight red hue and then the others are different yellows. The CLP soaked in the fastest by the way reflecting how thin it is.

Did Some Digging

I visited their website and also did some searching. KGW is a new firm so there really isn’t much info out there which meant I needed to reach out to Kohl Oettle, the owner of KGW who developed the oil. Scott had his contact info so we traded some emails.

Kohl was a tanker in the Marine Corp Reserve for six years and had developed a dislike for CLP as a lubricant – CLP stands for Cleaner Lubricant Protector just in case you didn’t know. Kohl pointed out, “We used CLP on everything, m4, m16, 240, m2, m48 etc, and in every application it burned off and ran off so quickly that I developed a real hate for all types of CLP. I wanted something that was thicker, handled heat better, and just lasted longer. “

That resonated with me because CLP is just way too thin for me. When I have big clunking parts, I need a thicker lubricant such as as oil or a grease to have reliable lubrication especially during break in. I still use CLP as a cleaner once in a while but I haven’t used it as a lubricant for probably 16 years — tt dawned on me that I started working on AKs around 2006 and CLP was just too thin to use as an assembly lube on those rifles so it’s been more like 16 years.

So I asked Kohl what set his oil apart from the tons of other products on the market. He responded, “It’s not trying to do everything. It wasn’t designed to be a cleaner. It’s a damn good oil and protector, without all the cleaners that make so many others thin, and less heat tolerant. I do have a very small amount of carbon deposit reducers in my oil, but just enough help control the carbon buildup and thus make the bolt reciprocate much easier. It’s not nearly enough to be used as a cleaner, and that’s on purpose. “

For the last seven years, Kohl has worked in industrial maintenance working on a variety of machines ranging from food processing to automotive parts manufacturing. As part of this, he learned that one of the most effective means of keeping a machine running reliably was to use the proper oil and grease.

What I found especially interesting was that Kohl tinkered with the the blend until he achieved the viscosity and lubrication he wanted through trial and error. He primarily had the AR-15 and similar rifles in mind when he was designing it but it will work on other pistols, rifles and shotguns as well. By the way, I mentioned earlier I thought it was about 30 weight – Kohl told me it’s a tad thicker than that.

When he was ready, he took to shooting classes and and shot thousands of rounds through a variety of weapons. He also sent out samples to people and a local gun store helped him sell his oil and collect feedback for 18 months. He took this feedback and further refined his product.

I respected what he did. Both Scott and I started our respective businesses and learned over time the same way Kohl has done.

Assembly Lube Testing

I used the KGW Enhanced Reliability Oil as an assembly lube for the fire control group, bolt catch, bolt, and bolt carrier. I grease the takedown pins so not there.
I ensured there was a thin film on both the top/front of the hammer as well as the bolt carrier.

My testing has been limited so far but I will update this post after my first range trip. I recently built two AR rifles and used Kohl’s oil as an assembly lube. I could tell everything was moving very easily. In this regard it worked great. Time is a challenge these days and I hope to get these rifles to the range in the next 3-4 weeks but didn’t want to hold up getting the word out there.

You can buy the oil direct from KGW’s website or you may find it at your local gun store as their business expands.

By the way, I don’t make any money off this post and Kohl didn’t ask me to. I just know what it’s like to be an entrepreneur trying to start a small business – I figured helping Kohl was the least I could do after all the folks who helped me.


Note, I have to buy all of my parts – nothing here was paid for by sponsors, etc. I do make a small amount if you click on an ad and buy something but that is it. You’re getting my real opinion on stuff.

If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@*********ps.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.


Super Secret AK Furniture Fitting Tool

Ok, now that I have your attention with that title, I often get asked how to fit the various furniture parts of an AK to a given rifle – the gas tube cover / upper hand guard cover, the lower handguard and the buttstock. Most of the work can be done with a secret tool – a slightly modified single cut file and patience.

For example, this is Palmetto State Armory’s Redwood furniture set on a Romy G kit I built.

Most of the time with new furniture, you need to remove material and a single cut file works great for that. With the pictured PSA Redwood furniture set, I needed to think the half circle ends of the gas tube cover and I also had to fit the lower hand guard just a tad.

This is an 8″ single cut Nicholson Handy File that I bought many years ago and modified. I prefer a single cut file so I can go slow and not remove material too fast. Just remember an old saying – “it’s easier to take more material off than it is to put it back on.”

Now here’s the trick to really make this tool work for fitting furniture – grind one thin side smooth – literally get rid of the file’s teeth. This will allow you to quickly and easy run the file right against a raised edge, such as the lips of the gas tube cover, and remove material that you want while leaving the raised edge untouched.

I find an 8″ file just the right size. 8″ is the measurement from the front edge, or “point” of the file, to the base of the heel – the bottom of the main body before the tang starts. The file shown is an 8″ Nicholson Handy File but any 8″ single cut or a file with single cut on one size and double-cut on another would work.

Any brand of file ought to work. Some come with a “safe” edge meaning no teeth. Just test it first to see if any of the teeth from the perpendicular surfaces protrude enough to cut – if they do then knock them down so the smooth surface can ride on the material you are working on with zero cutting happening from that side.

I used my big belt sander and removed all the teeth from this one edge and ensure it was smooth. I purposefully left the teeth on the other thin edge.

Just be patient – look at where the furniture is binding, remove a small amount and test the fit. In general, you want AK furniture to fit snug vs. rattling around. Patience is the key though – don’t rush things. Just keep inspecting, filing off a bit and testing over and over.

So everything is installed, nothing broke because I rushed and the end result is nice snug fitting furniture.

Summary

A single cut file with one thin edge ground is the secret tool but you need to be patient when using it. I can’t even begin to guess how many lower and upper handguards I have adjusted with this file over the years plus I have learned a bit more patience as well.

I hope this helps you out.

Simplify The Installation of AK Triggers With Our Slave Pin

The typical semi-auto AK trigger has four parts – the trigger body, disconnector, disconnector spring and pin. Installing it can be a challenge because you need to properly align the disconnector while sliding the pin through from one side of the receiver to another. For me, with big hands, this task takes more effort than I want.

This is your typical semi-automatic AK trigger group. On the left is the trigger body, top right is the disconnector, under the disconnector is its spring and at the bottom right is the trigger pin. The challenge is getting this all assembled inside of the AK receiver as the pin needs to pass from one side of the receiver, through one side of the trigger, through the disconnector to capture it, out the other side of the trigger and finally out the other side of the receiver. Trying to get it all to align inside of the trigger takes some patience.

The Solution – Use A Slave Pin

There is an easier approach. We can slide a properly sized dowel pin to serve as a “slave pin” during assembly to secure and properly align the disconnector and trigger outside of the receiver. This simplifies life tremendously. The unit is assembled outside where you can see what is going on, is lowered into the receiver and then the actual trigger pin is pushed through and it displaces the slave pin – the slave just exits the other side of the receiver.

This is the slave pin. Note how one side is beveled more than the other. That is the side that is inserted first. The bevel helps move things around during insertion and then the 5mm body provides the actual alignment for the trigger pin.
This is the assembled trigger group with the slave pin holding it all together.
Normally this would be in the receiver but I want you to see what is going on. As the trigger pin is inserted, it pushes the slave pin out of the way and it exits via the opposite receiver hole.
This photo shows how when the trigger pin is fully inserted, the slave simply drops out.
This is an ALG semi-auto trigger and you can see how slave pin is exiting the receiver as the trigger pin is installed.
So there’s the end result. A slave pin makes a world of difference. Note, that is one if our fire control group plates retaining the trigger and hammer pins.

Click here to order one of our AK Trigger Slave Pins

Click here if you are interested in one of our Fire Control Group Retainer Plates

In Conclusion

If you’re like me and want an easier way to install AK triggers, these new slave pins are the way to go!


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Video: What is the Best Way to Reload an AK? Kalashnikov Media Answers a Hot Question

You know, it’s interesting how people will argue over stuff on the Internet. Give them a picture of a stick and they will argue about it! Now, turn the topic to AK rifles and debating what is the right or wrong way to do something, things get colorful fast and a lot of energy is wasted over trivial points.

In this video, Vladimir Onokoy, who always does a great job, goes over different reloading approaches. Now most folks do not know Vladimir but I will tell you he is the real deal with considerable Russian military experience and armorer-level experience with the AK platform. In short, I would recommend you listen real close to what he says plus bear in mind that this is a Kalashnikov Media video and they know their stuff as well 🙂

Watch the Video

Normally I give some screen shots and make some color commentary but this video is only 3:05 seconds and seeing is believing.


I fully agree with his conclusion – train and become proficient. They all work the question is what works best for you and only training and experience can answer that.


Please note that all images were extracted from the video and are the property of their respective owner.


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PSA AK Webstore Links

Interested in an American made AK? Consider Palmetto State Armory (PSA) as a source. Click on the following links for the associated webstore categories for AK-related rifles, pistols and parts at PSA:

Video: Forgotten Weapons Reviews Soviet AK Magazines

In this short video, Ian gives a brief overview of Soviet magazines – notably the slab side, ribbed, waffle and bakelite. As always, Ian does a great job and this is worth a watch!

The first generation was a heavily built (over-built) magazine known as the “slab side”.
After the slab side, they developed the ribbed magazine that was copied by many countries.

To reduce weight they developed the aluminum waffle magazines- so named due to all the reinforcement ribs. It was relatively short-lived because it was not durable enough.
After the waffle mag, they moved to the Bakelite magazine that actually was a glass reinforced polymer. This gave them what they wanted – light weight and durability.
When the AK-74 was developed, they went straight to polymer and never developed steel mags. Note, other countries did build steel AK-74 magazines but the Soviets did not.

The Video


I hope you found that video useful. Ian is a wealth of information and you can learn more about his work at Forgotten Weapons.


Please note that all images were extracted from the video and are the property of their respective owner.


If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@*********ps.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.



Video: Matra Group Manufacturing AK-47 and AK-74 Steel Magazines: From Sheet Metal To The Finished Products

The AK-47 rifle and it’s “banana” 30 round magazine are classics of rugged functional design. While I’ve posted many videos and how-to articles relating to various rifle and pistol variants, I’ve not really covered the steel magazines at all.

I was surfing around and found Matra Group located in Bosnia-Herzegovina. In 2015 this small manufacturer produced a video showcasing their small facility that makes a variety of steel magazines for AK-47, AK-74 and even Lee-Enfield rifles. The Lee-Enfield may be due to those rifles being supplied to the Yugoslav Partisans in WWII to fight th axis armies.

In the video, they show employees starting with sheet metal and stepping through various steps including stamping, machining and spot welding. For the most part, you will see a very labor intensie process using older general purpose machines. If you like videos that showcase how something is made in and old-school fashion, you will find this very interesting.

Here they are cutting the initial sheet down into usable blanks.
Making the front piecee that will lock onto the front trunnion.
Spot welding the two body halves together.
Gettingg ready for final assembly.

Here’s The Video


I hope you enjoyed the video! I definitely found it interesting and informative. Just to be clear, I am not endorsing the magazines – I’m just showing their manufacturing process so I can then compare it to the manufacturing used to produce the Croatian AK-47 magazines that Apex Gun Parts sells.


Please note that all images were extracted from the video and are the property of their respective owner.


If you find this post useful, please share the link on Facebook, with your friends, etc. Your support is much appreciated and if you have any feedback, please email me at in**@*********ps.com. Please note that for links to other websites, I may be paid via an affiliate program such as Avantlink, Impact, Amazon and eBay.



My Favorite AK / Kalashnikov T-Shirts – May 2019

As my wife will tell you, I like T-shirts and, of course, I like AK rifles so the two go together! There are so many cool designs out there these days, I thought you might like to see them. Plus, since they are on Amazon, you know you will have their excellent customer service backing you up.


I hope you have some fun looking at the photos at least plus it is time to get ready for summer and having fun outdoors!


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