After many years of great plastic BB slinging performance the SR10 was getting loose in in a bunch of places so it was time to retire it to the parts bin. What to do, I have many replicas but really prefer to keep to one for regular field use. I needed something new 
Back to all the replicas and a KWA CQR MOD2 that had been collecting dust for years. I had replaced the upper with a metal one many years back. This is basically a new AEG, all nice a tight. Idea
OK it was decided, I'm going to build a MK18
I have not gone into a lot of details here, but shard the highlights and some specific parts I really like.
The old SR10, MOD2 and parts. My new favorite cylinder is a Lonex Stainless Steel Cylinder, this one is ported. Also a Matrix Silent Piston Head and matching Matrix Silent Cylinder Head. I also used these parts on a HK417D build I did and will share a few of those pictures as well. The barrel is a Madbull 6.01.
If you are familiar with the old KWAs and those 4 piece (pos) uppers you have experienced the wobble.
You can buy a one piece upper or try my little trick.
Here is the upper broken down.
Best cleaner for metal parts, don't forget the eye pro
Oh yes, the good old reliable J-B Weld
I used this same trick on my LM4 and even with the gas blow-back recoil the upper is solid.
Attaching the Picatinny rail takes some care. Fill the pocket on the rear of the rail and make sure you apply sparingly to the upper where the rail sits
Quickly clean up any J-B that may of squeezed out.
Dont forget the inside of the upper. Any extra J-B will interfere with the charging handle
Here is the assembled upper. Wait at least 24 hours before applying paint. This is Krylon Camo Paint (Khaki color). I really like this paint, it is inexpensive, very flat and easy to use. This color is a bit tan and doesn't match the Magpul FDE well, more on that later on.
You can see the MOD2 cylinder is ported for a short barrel, thus the new one. This gearbox is front wired, I need it rear wired.
Trigger contacts from the MOD2, I run 11.1 Lipos and mostly semi auto, its havoc on trigger contacts and they deteriorate very quickly. I have a solution I'm pulling from the SR10.
Yes, that's a BTC Spectre installed in its new home. Wire routing is key notice how they are laid out.
After lubing the one side I noticed I forgot to remove the wire hold down pins from the right gearbox side
These need to be filed down or they will pinch the larger wires of the BTC. All is good now, BTC and gears installed and box is lubed
The cutoff level and trigger safety lock are deleted when installing a BTC. That's the only thing I don't like about the BTC. When your AEG is in safe the trigger can still be pulled. I wont fire, just something to get used to.
Here is a closeup of the GB internal parts. I'm going to reuse the Madbull PX-02 piston that was in the MOD2. My SR10 had have the same piston in for 7 years, 100Ks of BB fired.
Don't forget the loctite on the piston head screw.
Teflon tape is a airsmiths best friend. I did not need it here, but sometimes you need to wrap the piston head seals before you install it in the cylinder.
All assembled notice the cylinder head port location
Ok, another fav part is the Godzilla 5000 motor, why? It's one powerful little spinner. You can see the PTS grip installed in the background.
Ok, remember I need to convert to a rear wire, the GB is complete, now the buffer-tube. I was going the use the buffer-tube screw and retainer from the SR10 (on the right) looks a bit tweaked to me.
I temporarily installed the retainer and marked it (left circle, notice the white under the wire) The right circle shows where you may nee to remove some metal from the sling plate so it wont pinch the wire.
Here is the retainer with the newly added notch for the wire. The right tools make this easy.
OK, now time for that sexy Danial Defense rail
Shims may be needed to hold the barrel securely. BTW this outer barrel is from the MOD2.
Upper assembled and installed. You can see how tan the upper looks in this photo.
Now the most difficult part
installing the stock. Almost there ...
Nice grips are expensive, and everyone has their favorite. Here is mine, unfortunately its from the SR10 and painted to match
How to remove paint ... yes I'm lucky I have a sandblasting cabinet. First attempt on plastic, I normally reserve this "glassbead" media for Aluminum or Magnesium, that's another story.
This worked very well and you dont' need a cabinet, you can do this outside.
the grip is all cleaned, but looks a bit weird.
Lets try a bit of silicone to bring back the orgional black color.
Light sprays and a little RUBBING
bring the color back. Now the sight. Sandblasted the outer shield of the FAKE Eotech and painted with my new Fav Flat Black Paint
did the same with the buffer-tube. This mat-flat black paint is Awesome, love it ....
Sharing "Zero Rust" with you.
All assembled with optics and a PEQ
I hope you enjoyed this overview. I will be posting a few pictures from my HK417 D build I did, but that will be in another forum.
Eye pro is also important in the shop,
Be safe whenever airsmithing.
