In an earlier post I mentioned that the front sight of my AK74U had developed a slight crack. Initially this didn't seem a big deal, but I forgot to do something about it and after a day's airsofting the crack opened up into a chasm!

Monkey metal (or pot metal) is the low grade metal that the Chinese use to make their metal cheapsoft AEGs. Unfortunately it is very brittle, actually more brittle and prone to cracking than good quality Western ABS I believe (ironically). And once it cracks, there is very little that can be done if - like my component - it is a part which is under stress or a moving part.

My first attempt to repair...

Tools: My trusty Dremel Multitool, with all it's nifty cutting, grinding and sanding attachments, plus some Araldite Precision two part metal glue, and finally some Araldite metal bonding putty.

First of all I thought I might simply get away with gluing and filling the crack, and then by adding some better bolts secure the sight more firmly.

1. I used the Araldite glue to bond the two halves of the crack, clamping the component together to force the tow halves of the crack to join firmly.

I left this the full recommended 24 hours, to set rock hard before loosening the clamps and going on to the filling stage... 

2. I then used the 'Plumbers Putty' to fill and smooth the line of the crack. I also hoped that by adding this layer of putty that it would help to reinforce the component when I inserted the new retaining bolts I had bought...

 
3. Unfortunately, as the above diagram shows, the filled crack (Pic 2) was not a strong enough bond to resist the strain placed upon it by screwing the bolts into it (Pic 3). The stress on the part when affixing the sling to the integral sling loop just reopened the crack, and moreover caused a second crack which resulted in the complete breaking off of the lower section of the part (Pic 4). Drat!

Second repair attempt - back to the drawing board!

Hhhhmmmm, ok. That didn't work, mainly because the 'pot metal' having lost it's coherence was now overly sensitive to any stresses or strains placed upon it. So something a little more drastic, and reliable would have to be thought of. And here is what I came up with...

1. First of all I completely removed any of the remaining jagged remnants of the old retaining block, so that there was a nice smooth gap between the the bottom parts of the sight (Pic 1).

2. Next I placed the sight back on the outer barrel of the AEG (Pic 2 - gray circle) and carefully drilled two opposing holes through the sight into the outer barrel. CARE MUST BE EXERCISED NOT TO DRILL ALL THE WAY THROUGH THE OUTER BARREL AND INTO THE INNER BRASS BARREL. If your drill or screw into the inner barrel, chances are you will deform it. Then I screwed in specially shortened bolts, attaching the sight to the outer barrel (Pic 2 - red bolts).

3. Finally, with the sight component firmly fixed to the barrel I filled in the underneath of the sight collar with the metal bonding putty. After this dried, I sanded it and applied the coats of paint. 

Here's the resultant repair job...

I'm fairly pleased with this repair, to the casual eye the mend seems to be invisible, plus the sight is more firmly fixed in place now and should even be up to my reattaching the sling.