How to properly mount your Heckler & Koch claw mount to your G3, HK 91 or HK license built rifle.

HK STANAG MOUNT

After the German Bundeswehr replaced the G3 with the G36 as their standard rifle, the market was flooded with surplus Hensoldt scopes and STANAG claw mounts. STANAG is a NATO acronym for STANdardisation AGreement. The scope/mount interface is designated STANAG 2324 in the NATO.

These mounts will readily mount to any HK G3, any HK license G3 made by FMP, EBO, MKE et al. It will also likely work on any G3 clone with a receiver built to HK specs. Other clones may have out of spec receivers, or does not have the mounting tabs at all. There have been reports of HK 90 series rifles which require removal of metal from the mounts to get a proper fit.

HK 91 rifles have a different rear sight base, and may require that the plastic bumper at the rear of the claw mount is removed. It is normally glued in place but you can easily pry it off with a small screwdriver.

The underside of the claw mount is marked "Schußrichtung" with an arrow. This mean "Direction of fire" in German. The arrow is to point towards the muzzle of your rifle. The number 1240-12-140-9932 seen in the pic is the NSN or NATO stock number. The dimensions of the screws attaching the scope to the mount are metric M6x10.5 mm. This means they are 6 millimeters in diameter and 10.5 millimeters long. Thread pitch is 1 millimeter. If replacements are needed, ordinary M6x10 mm will work just fine and should be available in any well assorted hardware store.

In some instances, even after removing the plastic bumper, the mount is still difficult to attach. There may be several reasons for this, e.g.

 1. The pressure pads may be binding, possible causes are rust or debris.

 2. The rifle's coat of paint -may- be to thick to allow the mount to seat properly.

 3. Receiver or receiver tabs are out of spec. More likely on various G3 clones.

Remedies:

Disassemble the pressure pads. They are attached with circlips inside the tunnel allowing use of the iron sights. When the circlip is removed, the pressure pads should come out along with seven torsion washers. If rusty or dirty, clean them with brake cleaner or similar and coat with your favorite gun oil. Remember to clean out the pressure pad seats as well. If the mount was bought from a dealer, try to return it for a replacement mount.

If you still have problems attaching the mount to your rifle, there is two options you can try.

 1.  Disassemble the pressure pads, and remove one torsion washer from each pad. Reassemble and check mount fit. If it still is to tight to attach properly, your receiver is probably out of spec. (You did remove the plastic bumper, didn't you?) If it is too loose, you may be able to craft some shims to replace the torsion washer you removed. Shims could be made from a set of feeler gauges.

 2. Remove material from the pressure pads. This requires a very steady hand, and is not recommended. If you decide to go this route, the risk is yours.

3. There have been issues with the mounts not fitting in the groove in the rear sight base on HK 91 rifles. If this is a problem, then it will be necessary to remove material from either the rear sight base or the claw mount itself. This issue seems to be fairly rare though.

Note on STANAG Rings made by a third party

Various vendors offer so called STANAG rings that will fit on the STANAG claw mounts. These may work very well if you intend to mount a scope that don't have the STANAG interface. There is one thing that needs to be considered though. The scopes that have the STANAG interface has a fairly short eye relief, approximately 60 millimeters or 2.36" whereas most variable magnification scopes has an eye relief of 75-80 millimeters or 3-3.15". To add to the problem, a variable scope will often sit further back on the mount because of the magnification adjustment part of the scope. Because of this, care should be taken when considering which scope to select. Otherwise, a shoulder stock extension may be required to obtain proper eye relief. A better solution than using STANAG rings, is to get a weaver or picatinny rail with STANAG interface. These are available from various sources, e.g. Leapers or the A.R.M.S.® #06™ II Adaptor.

Various scopes and mounts for reference:

 1. Hensoldt model 1 on a SIG SG 550 series STANAG interface mount.

 2. Hensoldt model 2 on a HK STANAG interface claw mount.

 3. Hensoldt FERO-Z on an A.R.M.S.® #05™ Mount.

 4. Schmidt & Bender 1.5-6x42 on a HK claw mount with built in 30 mm rings. 1/2" inserts available.

HK MOUNT w/BUILT-IN RINGS

The info in the STANAG mount section basically applies to the mounts with built-in rings as well, as the rifle/mount interface is the same.