Just before I start, let me say one thing. If you're new to airsoft and are considering buying a gas blowback Mac 11 as your first piece, DO NOT.
Chances are very high that it'll have a wide number of issues which you won't know how to fix. If you want full auto, go with an AEG instead.
Just to anyone unaware, The KSC and KWA are the exact same gasblowback made by the exact same company. KSC is made for the Japanese market, therefore has all the Ingram trademarks. The KWA was made for export around the world so they were unfortunately removed for obviously copywrite issues. If you can, get the KSC. As you'll look a lot 1337er than all the KWA users
Now one of the most important rules of the KSC m11a1 which you should do without even thinking,
PULL THE BOLT BACK BEFORE INSERTING THE MAG.
After "Not for beginners", this would be the next thing written across the box in big red letters. Not doing so will fatigue a plastic internal part of the bolt and eventually it will snap. (The option is there to upgrade to a magnesium bolt. In which case, you will no longer have to do this)
Anyway, on to some of the problems.
The main issue I had originally with mine was incorrect feeding. Over half the bbs were hopping out the ejection port rather than going down the barrel. Either that or they were all getting stacked up on top of each other, jamming the blowback function.
The easiest way of solving this problem is switching your brand of bbs. The primary culprit seems to be excel. Their diameter is slightly smaller than other brands. As a result, the bbs won't stay in the magazine properly and release, jamming everything up. I even found that an accidental knock to the top bb in a mag could send the rest spewing out after it.
This should solve the ejection port problem. If not, then your issue is more than likely with the bolt cycle itself or the hop up rubber.
There are a number of issues which can cause the bolt to cycle incorrectly. The main one is usually lubrication. The mac11 really does need a lot of it. It's usually a good idea to strip it right down (Bolt and all) and clean it out regularly. If you're using it for skirmishing, after every game.
However, there are a couple of points which need to be avoided. There are two rubber seals which, rather annoyingly soak up silicone oil. If you lubricate these too much they will expand (Possibly jamming things) and crack.
One of the rubbers is located where the hop up is. (Where the bbs feed into the barrel). The other is on the top of the magazine.
You can easily see the hop rubber there in the middle of the picture.
Applying lithium grease to a couple of parts of the bolt is also known to greatly improve cycle rates. (Something I haven't had any experience with myself. I'll add to this when I get a chance to try it out)
The second major problem (And turned out to be another huge issue with mine) is the gas itself. Use decent green gas. I originally bought ICS with the Mac and it didn't work once. Either use ASG branded stuff or propane. I've actually found that the propane gives it a little extra oompfh (yes that is a technical term) which does help a bit with the cycling.
However, propane and good green gas will not always work 100%. Gas needs heat to expand. As the Irish climate isn't exactly tropical, some blowbacks have trouble working here.
The best way of avoiding this is having more than one magazine. If you only use one, repeatedly filling with gas will cause so much cooldown that it won't be able to expand. Resulting in the bolt eventually only cycling about half way.
Take down guide.
This is more or less everything you need to know to take the Mac11 down enough so it can be cleaned.
First thing to do is remove the stock. I'm sure you don't need a picture of this...
Next, remove the front pin. You push the small tab down and then press it through. Tricky enough to figure out but once you do, you feel like a bit of a pleb for being so confused. (Well I know I did anyway)
And it's out. Hurrah.
Do the same with the other pin.
Now with no pin in the front, the top part of the receiver should come away
Notice the large hook at the end of the bolt just under the screw. This hooks into the lower receiver and takes a bit of jiggling to get in and out. It's not difficult, just be aware that it's there.
Lower receiver
This is probably the trickiest part. Taking the pin out of the bolt to separate it from the upper receiver. In this image the pin is turned sideways. It acts like a second safety. We don't want it like this.
We want it like this
Pull the pin the whole way back as if you're cocking the Mac to shoot. You'll notice that there are two holes in each end of the slot where the pin flies back and forth. The back hole is the biggest one and is where you'll be pulling the pin out. Getting the damn thing to come out can be quite difficult. I almost gave up while taking these pictures. But decided to persist. Eventually it popped out.
You can now remove the bolt from the upper receiver.
Bolt itself. (Reversed to show spring)
And that's it folks. Things you'd want to lubricate are every side of the bolt, inside the upper receiver wherever the bolt makes contact. (which is more or less all of it). The lower receiver. Trigger mechanism. Everything that moves.
