*This article makes use of the KSC Glock 18C Exploded diagram in the KSC Glock 18C supplemental manual. I'll try to get it posted, eventually.
For a very long time I have heard numerous complaints about Glock 18Cs with metal slides not firing on semi-auto. I have never heard of any problems with semi-auto occurring on a G18c with a plastic slide.
So, knowing that the problem could probably be attributed to the metal slide, I sat down, learned how the G18c works internally, and found out what is causing the problem.
First of all, I want to say that the metal slide problem may be isolated to 1 particular brand. Airsplat.com, the company from which I purchased the slide, claims that it is manufactured by KSC. The slide has no Glock trade markings or KSC manufacturer markings. I purchased it at airsplat.com for about $60 USD.
Most people who are experiencing this problem probably have the same type of slide that I do.
In reality, I suspect that the metal slide that airsplat is marketing is NOT manufactured by KSC; I am making inquiries at this time to both Airsplat and KSC.
On to the problem.
The first thing that you notice when you look at the metal slide on your malfunctioning G18c with a metal slide is that the metal slide itself has been milled in such a way that it does not lay close on top of the frame of the G18C. There is a visible gap between the frame and the slide, especially towards the rear of the gun. Compare the gap to that of the original, plastic slide.
You will notice the plastic slide has no noticeable gap between the frame and the slide.
Simplified Problem Explanation:
Basically the improper milling of the slide is to blame for the gun not firing on semi-auto. It is because the slide rests too high on the frame that the internal SLIDE parts cannot completely and properly interact with internal parts inside the FRAME. The slide needs to be milled so that the groves that hold it onto the frame are a bit higher, and therefore, hold the slide lower on the frame.
Advanced Problem Explanation:
This problem basically involves 3 different parts inside of the Glock 18C. The parts will be referred to as their numerical designation in the KSC Glock 18C manual. Short of explaining how the entire KSC Glock 18C works, here is a description of the problem and why it happens. Have your exploded diagram and pistol handy to check out things for yourself.
The Glock 18C has 2 separate fire-modes: Semi-Automatic and Fully-Automatic. The switching mechanism on the slide does nothing except to lower a small metal plate (part 261) so that it can come into contact with the nub on part 92.
At least that is the only thing the slide does that is relevant to the problem at hand.
With the slide removed: make note of the small nub on the top-rear of part 92 that projects only slightly from the frame.
As you can see on the diagram, part 92 is attached directly to the trigger inside of the frame.
For each pull of the trigger, part 92 moves towards the rear of the gun; at this point, one of two things is going to happen based on whether part 261 <font color="green">IS LOWERED </font id="green">by the selector switch (which would normally yield semi-auto fire) or if it <font color="red">IS NOT LOWERED </font id="red">(which will yield fully-automatic fire).
*Lowered part 261= Semi-Auto Fire
*NOT Lowered (Raised) part 261= Full-Auto Fire
Remember the nub on part 92? As part 92 is moved backwards during a trigger pull, that nub will make contact with part 261 (**ONLY if part 261 is in the lowered position). Here's where the problem occurs. If the slide is resting too high off the frame, then part 92 will never make contact with part 261, even if part 261 IS in the LOWERED position.
The slide is just too high. Too far away for the nub to reach part 261.
So now that we know that part 92 is not making adequate contact with part 261, and we know that is causing the problem, we must examine the function of part 266.
Part 266 is basically a lock. When the lock is engaged, the hammer on the pistol will not release once the pistol has fully cycled once.
If the lock (part 266) is not engaged, then each time the G18C cycles, the hammer will be released once again to fire the next shot automatically. This automatic fire will continue until the trigger is disengaged.
*Disengaged Lock (part 266)= Full-Auto
*Engaged Lock (part 266)= Semi-Auto
So if part 266 is the lock, then we need to know what engages or disengages the lock. It turns out that part 92 is responsible for engaging the lock (part 266).
If the nub on part 92 (and subsequently the whole part 92) is forced down by part 261 as it travels towards the rear of the gun, it will not disengage the lock (part 266).
Uninterrupted, part 92 will normally <font color="red">DISENGAGE </font id="red">the lock (part 266) and allow fully-automatic fire, but if the selector switch is set to semi-automatic and part 261 IS LOWERED (as it should be in semi-auto mode) then part 92 <font color="green">WILL NOT DISENGAGE</font id="green"> the lock and the gun will fire in semi-automatic.
So basically:
-Nub on part 92 is too far away from part 261 because of incorrectly milled slide.
-Part 261 is not able to force part 92 down far enough.
-Part 92 is not able to keep from disengaging the lock (part 266).
-The hammer is not locked by part 266.
-The Glock 18C is not able to keep from firing on full-auto.
I'm sure you would like a solution... there are a few avalible that I can think of:
1. If you are still covered under the retail warrenty, return the item.
2. Re-mill the slide (Yeah right!) [xx(]
3. Add more material to the nub on part 92 or hammer part 92 out to make it project further into the slide. --Doing this may compromise the integrity of part 92.
4. File down the parts of part 92 and/ or 266 so that they only need minimal contact to disengage to lock on the hammer. -- Doing this may be unsuccessful if the nub on part 92 makes minimal or no contact what-so-ever with part 261.
*It would NOT be wise to add material to part 261.
I hope everything made sense to you. I also hope that there are some more viable solutions to the problem out there.
As I said, I will be getting in contact with Airsplat and KSC to find out who the true manufacturer of the slide is. I am going to pursue a refund. If things work out for me, I will let everyone know how I did it and give them the means to do the same.
