PSA for HK G3 owners

[Micael]

As some may be aware the Swedish armed forces use the HK G3 to some extent still (designation AK-4 here).

An issue with the breechblock has been identified, specifically hairline cracks that can be tricky to spot if you don’t specifically look for them. Needless to say that if this evolves into a complete failure there may be ”interesting” consequences. Note photos below.

So, if anyone here happens to own or use a G3 I would recommend a close inspection to avoid unpleasantness.

Same photo in duplicate, right hand version with cracks marked:

[jemhouston]

I have one Century Arms C93, not too many rounds through it. Will keep an eye on it. Thank you.

[gtg947h]

I'd be interested to see the internals of the assembly... not being familiar with it and just seeing the outside, I'd expect cracks to be forming elsewhere

[Micael]

I'd be interested to see the internals of the assembly... not being familiar with it and just seeing the outside, I'd expect cracks to be forming elsewhere

I had one out during the last few days but I didn’t have time to take photos during the occassions when I had it apart. In general I would say that it is a pretty complicated mechanism compared to many other guns, many interlocking parts, rotations etc. I’ll see if I can find any photos online.

[Edit] The rollers seen where the cracks are spreading from pops in and out of the body depending on what position the whole thing is in during operation. When in the fully extended position they are pressing against other components. As a complete guess I would say that it is possibly at that point where the strain on the whole thing is at its greatest, which is causing the cracks.

[Nik_SpeakerToCats]

With exception of ring on the right, look like propagating from too-sharp internal angles.

IIRC, wasn't the 'Comet Lesson' that wary radii mitigate stress focii ??

Um, trad way to check was identically machined Perspex between crossed polarisers...

[Micael]

With exception of ring on the right, look like propagating from too-sharp internal angles.

IIRC, wasn't the 'Comet Lesson' that wary radii mitigate stress focii ??

Um, trad way to check was identically machined Perspex between crossed polarisers...

Possibly. I’m leaning towards it not being a material quality issue since the rumor mill claims that examples of this have been found amongst guns from all three of the manufacturing sites that we have guns from. That is to say HK in Germany, Husqvarna and Carl Gustafs Stads Gevärsfaktori in Sweden. So it seems more likely that it is something to do with the design.

[Micael]

Forgotten Weapons just released a video looking at the AK4, showing the differences compared to the standard G3 if anyone is interested:
https://youtu.be/n8C5CzYQgqQ

[Nathan45]

Interesting the had a modification just to reduce damage to blank brass to make them easier to reload. Highlights frugal practical training.

[Micael]

Interesting the had a modification just to reduce damage to blank brass to make them easier to reload. Highlights frugal practical training.

Yeah, there’s pouches as well that you can mount to them in order to collect the brass easily. They also help with keeping the brass in good shape for reloading.

[Nathan45]

Did you reload live ammo as well or just the blanks?

[kdahm]

Forgotten Weapons just released a video looking at the AK4, showing the differences compared to the standard G3 if anyone is interested:
https://youtu.be/n8C5CzYQgqQ

Best part of it was a commenter there recognized the serial number as the one he had decades ago in Swedish service. It's pinned as one of the top comments.

[Micael]

Did you reload live ammo as well or just the blanks?

The brass is only used for making blanks (the type with wooden bullets). Considered to be too much of a reliability risk with live ammo.

[Micael]

Forgotten Weapons just released a video looking at the AK4, showing the differences compared to the standard G3 if anyone is interested:
https://youtu.be/n8C5CzYQgqQ

Best part of it was a commenter there recognized the serial number as the one he had decades ago in Swedish service. It's pinned as one of the top comments.

It’s not uncommon that people remember their rifle serial numbers after many years. I’ll admit to not remembering mine but some units drill it into their conscripts particularly vigorously. But neat coincidence that that guy happened to be a viewer.