KWC Mauser M712 Repair - Shooting Too High / Hop Up Removal

I love my Mauser M712 by KWC. Nice blowback. Full metal. 

Ok, the sight is shite. I can hardly see the front sight, which is the same as the original design. 

The main problem though is that it is shooting way too high. At 5m I had to aim about 2 inches lower than POI. I tried it at 15m... it was shooting almost 8 inches too high.

There were two possible culprit. 

Most owner of one of these will know that there is a bit of a barrel wobble. One can fix this by tightening the barrel shroud screw. Unfortunately this is located at the lower part of the shroud, and it will inevitably pushes the barrel upwards, making it shoot high. 

If you remove the barrel shroud, the actually barrel itself is quite floppy. It has a fair degree of upwards and downwards play. 

Shooting it as it is however, it does group fairly well, for a plinker. This is a grouping target from 5m.



And if you try hard enough, you can get a decent score with it. Here is 2 strings of 5 from 5m. I had to aim in the white at the level of the NSRA logo while keeping it in the middle. A real struggle!



I have tried various fixes, including putting some tape on the barrel, but that is counteracted by the barrel shroud screw.

Time for something more drastic. Time to open her up beyond the field strip...

If you don't know how to field strip it, don't even make a start. 

Next you need to remove the bolt screw. It's a size 3 allen key.  Keep the hammer down with your thumb while you unscrew it.



Then remove the two locking pin thingy... it is just held on by the bolt spring now. Take the space out before the main one might help.

This photo is upside down.





Now you can remove the top frame from the bolt and mechanism / barrel assembly.



And you can see how the barrel is droopy.





Now this is a bit of a bodger moment. You can do it properly by opening up the mechanism and take the barrel out. I didn't do that as there are lots of springs inside, and it will be a real bugger to put back together. There is a video on someone trying to put theirs back. I didn't want to do that.

"Fortunately" the barrel assembly is so poorly thought out that you can take it out by just prising the front part open, and gently pull it out. It is held on by a rubber grommet/hop up, two other pieces that holds the barrel on the frame, and the barrel itself. Be gentle with this part. Don't break anything now!



Here's the barrel and the two "spacers"



Can you see the hop up?



As I said it is still shooting upwards from 15m. This gun does not need hop up, especially if you want to try shooting from longer distance, or actually the elevation settings of the sights for aiming!

Another bodger moment. I took my craft knife out and slowly chip away at the hop up. 



And eventually got there.




Now put it all back together...

This time I'm going to glue it all up. I only have blue loctite, so that will have to do. I have tried, and failed, to tighten the barrel/frame joint by shimming it with some thin metal (aka aluminium foil!). Didn't work. Still a bit of wobble. So loctite it is.

Clamp it all up for an hour, and it is now rock solid.



And put it all back together again.

Initial result seems good. No grouping photos to show yet as I need to do more testing. It is shooting about 1" high at the lowest sight setting from 5m, so at least there is something I can use to with with for target shooting. Raining this am, so will try and put some targets up later today or another day...

But it looks good for now.