SKS to AK Magazine Adapter
Gunsmith Installation & Fitment Guide
Overview
The TNA SKS to AK Magazine Adapter is our own take on the SKS-D/SKS-M concept, allowing a compatible SKS to accept AK-pattern magazines.
The system consists of three primary adapter components:
- Magazine Stop
- Front Clamp Assembly
- Magazine Catch Assembly
The production components have been multi axis CNC-machined, cleaned up, and nitrided. The design incorporates several features intended to provide a secure installation while accommodating the dimensional variation found across SKS rifles.
1. Adapter Components
Magazine Stop
The magazine stop is manufactured from carbon-fiber nylon and occupies the area of the original SKS magazine-catch arrangement.
Its final production dimensions are intended to provide a straightforward fit in the rifles we've tested.
Front Clamp Assembly
The front clamp assembly secures the forward portion of the adapter.
The clamp uses spring steel and is designed with a reinforced profile that provides rigidity while retaining some flexibility.
The assembly incorporates an M6 screw and a tensioning/jacking screw.
The jacking set screw allows additional pressure to be applied between the clamp and the bottom of the barrel, increasing the clamping force when required.
Because the clamp is spring steel, it can flex under tension rather than permanently deforming.
Magazine Catch
The magazine catch provides the locking and release function for the AK-pattern magazine.
The production version includes a spring to provide positive return and engagement.
The catch is designed so that the magazine can be inserted using the normal AK-style rocking motion.
2. Initial Rifle Inspection
Before fitting the adapter, inspect the individual SKS and identify the rifle's manufacturer, variant, and relevant dimensional characteristics.
SKS rifles can vary considerably between:
- Countries of origin
- Manufacturers
- Factories
- Production years
- Individual rifles
The production adapter was developed around the Chinese SKS rifles used during testing, but other rifles may require additional fitting.
Inspect the receiver, trigger group, factory magazine-catch area, and surrounding interfaces before beginning the installation.
3. Removal of the Factory Magazine Catch
The factory SKS magazine-catch arrangement is removed to make room for the adapter components.
After removal, inspect the mounting area and verify that there is no damage, interference, or abnormal wear that could affect installation.
The replacement magazine-stop component occupies this area.
4. Magazine Stop Installation
Position the carbon-fiber nylon magazine stop in the receiver's original magazine-catch area.
The production part is designed to slide into position without excessive force.
Once installed, verify:
- Correct seating
- Proper alignment
- No unwanted movement
- No interference with the trigger group or bolt
- Correct relationship with the magazine catch
5. Trigger Group Interface
The adapter includes a component that interfaces with the SKS trigger group.
This component can move within the trigger-group area in a manner similar to the original SKS magazine-release arrangement.
The purpose of this movement is to accommodate differences in the dimensions of the original components and provide the required interface for the adapter.
Rifle-to-Rifle Variation
The rails and corresponding surfaces within this area can vary in thickness between SKS rifles.
If the dimensions of the rifle differ from the production adapter, the slot/interface may require fitting.
The production dimensions used during development were based on the Chinese SKS rifles in the tested batch.
Check the actual rifle rather than assuming another SKS will have identical dimensions.
6. Front Clamp Installation
Install the front clamp assembly around the designated portion of the rifle.
The clamp incorporates an M6 screw and the spring-steel clamping component.
The clamp only requires visual alignment to be perfectly square with the rifle. The important consideration is that it is properly seated and provides the required mechanical engagement.
The spring-steel construction allows the clamp to maintain tension while accommodating minor positional differences.
7. Clamp Tension Adjustment
The integrated jacking screw provides additional adjustment for the front clamp.
The screw can be used to apply additional pressure against the bottom of the barrel and increase the clamp's engagement.
Adjust the assembly while monitoring:
- Clamp position
- Contact surfaces
- Overall adapter alignment
- Magazine position
- Mechanical security of the assembly
The clamp should remain properly seated without excessive deformation or interference with the rifle.
8. Magazine Catch Installation
Install the magazine catch into the adapter assembly.
The production version includes the return spring.
Check the catch throughout its range of movement and verify that the spring returns it positively.
With the adapter installed, verify that the catch provides positive engagement with the intended magazine.
9. Bolt and Receiver Work
This installation is more involved than the TNA SKS-to-AR15 magazine adapter.
The conversion changes the original relationship between the SKS bolt, magazine, receiver, and magazine system.
The original installation requires additional receiver work and bolt modification to accommodate magazine changes with the bolt closed.
The gunsmith should evaluate the individual rifle and perform the required modification using the appropriate shop procedures.
Following the modification, verify that the bolt, receiver, magazine, and adapter all operate together correctly.
10. Bolt Hold-Open Function
The adapter does not retain the original SKS magazine-fed bolt-hold-open function.
With this configuration, removing the magazine allows the bolt to close.
Some AK-pattern magazines incorporate a last-round hold-open feature through the magazine follower. These magazines may provide a last-round hold-open function independently of the adapter.
The adapter itself does not provide this function.
11. AK Magazine Fitment
AK-pattern magazines are not dimensionally identical.
Variations can occur between manufacturers, countries, factories, production lots, materials, followers, and magazine geometry.
For this reason, final fitment should be performed around the magazine type intended for use with the rifle.
During development, both metal and polymer magazines were considered, but different magazine constructions can require different fitment.
If a customer intends to use multiple magazine types, each type should be checked individually.
12. Magazine Capacity & Fitment Issues
During testing, we encountered instances where a magazine would fit with four rounds but would not properly seat with five rounds.
This can be caused by the position of the magazine's internal rivet.
The rivet limits the movement of the spring and follower. Depending on its position, it can affect how much the follower and spring compress when the magazine is loaded.
If a compliant five-round magazine fits when partially loaded but will not seat when loaded to its legal capacity, inspect the magazine's internal geometry and rivet position.
Possible solutions include using a different magazine or having the magazine properly corrected by a qualified professional.
Do not assume that every magazine with the same nominal capacity will have identical internal dimensions.
13. Magazine Selection
For the most consistent installation, establish the intended magazine type before completing final fitment.
Ideally, use magazines from the same manufacturer and production lot.
This minimizes dimensional variation between individual magazines.
If multiple magazine types are to be used, expect that each may require separate fitment verification.
A setup optimized around one magazine type may not provide identical results with another.
14. Final Adapter Inspection
Once all components are installed, inspect the completed assembly as a complete system.
Verify:
- Magazine stop is properly seated.
- Front clamp is secure.
- Clamp tension is appropriate.
- Magazine catch moves freely.
- Magazine catch spring provides positive return.
- Magazine locks securely into the catch.
- Magazine releases correctly.
- Trigger-group interface is free of unwanted interference.
- Bolt and receiver interfaces are properly addressed.
- Intended magazines seat correctly.
- The completed rifle has no abnormal interference or movement.
15. External Appearance
The completed installation keeps the majority of the adapter concealed within the rifle.
From the exterior, the primary visible component is the magazine catch.
The adapter's branding is also largely concealed once installed.
The completed installation therefore maintains a relatively clean appearance while providing the new magazine interface.
16. Stock Considerations
The conversion uses internal space that may have been occupied by portions of the original SKS configuration.
Depending on the stock being used, the gunsmith should verify that the stock does not interfere with the completed adapter installation.
Some aftermarket SKS stocks may already provide the necessary clearance, while original military-style stocks may require additional consideration.
17. Final Fitment
The completed adapter should be evaluated using the actual rifle and intended magazines rather than relying solely on measurements from another SKS.
The key objective is consistent mechanical engagement between:
Rifle → Adapter → Magazine Catch → Magazine
Because of the variation inherent in the SKS platform and AK-pattern magazines, final fitment should be treated as an individual installation rather than a universal drop-in process.
18. Canadian Compliance
For Canadian installations, verify that all magazines used with the completed firearm comply with applicable Canadian magazine-capacity requirements.
A magazine's external body capacity does not, by itself, establish its legal capacity.
The completed installation should only be supplied with magazines that meet the applicable requirements.
