Building a Wieger clone is relatively straightforward in comparison to most AK builds but there are a few critical modifications that must be done.
Our handguard retainer is specifically designed to fit the JMAC Customs GBC-13 gas block. We do NOT guarantee fitment with any other gas blocks.
Before carrying out any modifications to the gas block please check the following parts fitment and dimensions!
- Gas piston hole
We've found that sometimes the gas piston hole is drilled at a slight angle or not centered within the gas block. This results in the gas piston binding within the gas block. Unfortunately this issue is difficult to identify until your barrel and receiver are installed, make sure to test fit your bolt carrier before pinning your gas block.
- Barrel journal hole
Just like the gas piston hole, the barrel journal hole can be drilled at a slight angle or not centered within the gas block. If this is the case we recommend getting a replacement from JMAC Customs.
- Varying external dimensions
The wax casting process used to manufacture these gas blocks can have varying external dimensions (not critical for traditional AKs). We've found external dimensions can vary by ~0.3mm and the bottom portion around the barrel hole may be out of round. This could result in the handguard retainer not fitting, if that's the case we recommend enlarging the handguard retainer hole.
If your gas block checks out then all you need to do is remove this small nub on the top of gas block. This is easily done with a bastard file.
Gas Tube
A smooth gas tube without upper handguard retainers is required to fit within the handguards. We recommend a saiga gas tube with a tension spring (AMD65 gas tubes are too short)
If you'd like the gas tube to look similar to the EG Wieger tubes the external heat shield can be removed by cutting through the 4 spot welds.
These "wings" will need to be removed to fit within the handguards. This is easily done with a bastard file, belt sander or bench grinder.
Handguard Retainer Staking
We recommend staking your handguard retainer locking bar to keep it captive with the handguard retainer. This can be done with a large roll pin punch.
Barrel Component Fitment
It is important that the basic AK assembly specs are followed, AKM assembly drawings can be found here thanks to Robert Forbus! Gas block, gas tube and rear sight block fitment are critical for ensuring your handguards fit properly.
Rear sight block should not be pressed on passed the trunnion ears. Gas block should not be pressed on to the point that your gas tube bottoms out.
The distance from the front of the receiver to rear of the gas block should be ~231mm.
Test fit your handguards before pinning your barrel components!
Wieger 5.56 Magazine Fitment
Wieger magazines have unique dimensions in relation to 5.45 and 7.62 magazines, likely to prevent them from being used in 5.45 and 7.62 rifles. The main tower width (~24.5mm) and height (w/ ejector clearance cut) is AK74 spec. The front width (~21.5mm) is AKM spec but with AK74 height.
In order to fit, either the magazines or the receiver and front trunnion will need to be modified to accommodate.
Trunnion Modifications
Bullet guides will likely need to be removed prior to machining. These modifications will still allow 5.56 AK74 spec magazines to function.
AK74 Trunnion:
Machine green highlighted area width to ~21.5-22mm (measure your mags)
Yellow highlighted area may need to be machined to 27mm (AKM spec) for rivets to fit with mags.
WBP 5.56 Trunnion:
Machine green highlighted width to ~21.5-22mm (measure your mags)
KUSA KR103/AKM Trunnion:
Machine green highlighted area to the depth of ~7.2-7.3mm measured from top of lugs (red highlight)
Updated - 2/9/24