DIY: Fixing a KSC Glock 18c Firing full auto in Semi

[e-luder]

Ok. So I just fixed 4 KSC Glock 18c's in the past two days. And I'm getting emails from friends asking me to fix theirs. Though all of them have their different problems, a common one among all of them was that their gun CAN'T SHOOT SEMI WHILE SEMI-ENGAGED. IT WILL SHOOT FULL AUTO NO MATTER WHAT.

I realize that this is probably of older knowledge now as the gun is super old.
So for the sake of people having this same problem and for the new guys on the forum that might be running into the same problems, here is a quick do it yourself fix.

Now, I don’t recommend you doing this if you have a gun technician readily available. Take it to them first and have them fix your gun for you. I also don’t recommend doing this if you don’t feel comfortable taking the slide apart. There is a small spring, part 262, that can ‘spring‘ out that you can never find ever again…ever. You have been warned.

How it works:

In order to diagnose the problem, first we must understand how the internal switch selector works and how it should interact with the frame assembly and its internals.
Get out your parts diagram because you need to refer to the specified parts to understand how it all comes together.

Have your gun disassembled.

See the nub on top of the trigger bar (part 92)? That part needs to interact with the blowback assembly to engage the full auto or semi auto functions of the gun.

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The primary function of the trigger bar (part 92) in regards to the fire modes is for that little nub on the trigger bar to make contact or not with a small metal bar on the blowback assembly depending of course on how you want the Glock 18c to shoot. This little bar is part 261.

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Depending on the position part 261, the gun can either shoot full auto or semi auto. If the part 261 is lowered, it can’t make contact with part 92. Thus attaining a full auto function. If it 261 is raised, the gun should fire in semi auto mode.

Follow so far?

Now, in order for the gun to raise or lower part 261, a small “wheel” or cog is installed beneath part 261 to pivot around selecting semi or full auto. This part is 260. Part 260 is the direct link between the external fire selector (part 255) and part 261. Thus, if you turn the external fire selector, part 260 will either raise or lower part 261 (depending on how you want to shoot the gun).

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That’s how the fire selector mechanism in a nutshell.

The Problem:

While there are many causes for the KSC Glock 18c firing full auto semi mode, there are only really two cascading causes.

The problem stems from the poor design of the Glock itself and the materials used. There are too many moving parts. The problem then carries over to prolonged usage that wears the parts out very easily. Couple that with improper use of lubricants, and you’ve a gun that can only shoot full auto when it should have a secondary mode.

The secondary, give or take, root cause is that most after market metal slides are not milled properly along the bottom edges. All of the four Glocks that I’ve fixed had the aftermarket slides that sat a bit higher than the stock slide. Thus, lifting the whole blowback assembly higher than it should primarily sit therefore preventing part 261 from interacting with part 92.

Part 261 and 260 are the culprits for the problem. If the two can’t work together to make contact with the little nub on part 92 while semi auto is selected then the gun will shoot full auto.

Of all the four Glocks, both part 261 and 260 were worn thin. These are the two parts that we will be working on to create a good contact point to engage part 92 on Semi.

The Fix:

Now, I don’t recommend you doing this if you have a gun technician readily available. Take it to them first and have them fix your gun for you. I also don’t recommend doing this if you don’t feel comfortable taking the slide apart. There is a small spring, part 262, that can ‘spring‘ out that you can never find ever again…ever. But if you’re brave enough, here is the fix.

The main goal here is to create the proper raise for part 261 so that in can interact with part 92’s nub while on semi. Thus, we need to ‘add’ a very thin layer of metal to part 261 or subsequently, reinforce part 260.

Again, I must entice you one last time, to take the gun to a technician FIRST before attempting this.

Here is a list of items that I used to for the fix:

1. Gorilla Glue
2. A very thin piece of copper

Procedure:

Step 1: Completely disassemble the slide. Take out the BBU. Make sure that you don’t lose part 262. It is very small

Step 2: Remove Part 261. Again Make sure that you don’t lose part 262. It will spring out.

Step 3: Remove Part 260. That’s it with the BBU. DO NOT DISASSMBLE IT FURTHER.

Step 4: ***Note: You need to pick which part you want to modify. You can’t have both of these parts modded. Otherwise, you will create the adverse effects of the gun firing semi on a full auto setting***

Working with part 261:

There are two places that you can ‘pack’. First is the rounded nub on one end. The second is the middle bar. Refer to pics.

photo copy 5.jpgThis is the Bar.photo copy 10.JPGThis is the Nub


Now, apply some adhesive on either part of the piece and immediately place the thin piece of metal. Make sure that the adhesive, does not leak all over the place while at the same time give the proper amount to hold the thin piece of metal in place. Keep in mind that part 261 is a high-stress part so the packing needs to sit firmly in place.

Wait for the glue to dry. If there is spillage over the side, DO NOT SAND IT OFF! Get a scalpel and cut the access glue off. Make sure that part 261 fits back into the BBU. It must move freely. Sanding would negate the purpose of this exercise.

Working with Part 260.
***NOTE: If you opted to pack the bar on part 261, YOU DO NOT NEED TO THIS***

For part 260, you need to pack the flat end. Not the Rounded end. Same step as above need to be taken.

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Step 5: Let everything dry. It is very important for you to let the adhesive bond with the metals to achieve maximum efficiency. I used industrial glue that hardens very slowly over time so I let it sit for about a day before putting everything back together.

Step 6: Re-lube and reassemble and voila. The gun should work on semi auto.

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The Permanent Grade fix:

If you have the tools, you can solder. You can just melt some of the solder and let it bond with either part and that should create adequate packing.

And there you have it. A quick fix. Worked for me.

Now, It is important to note that you must lube your gun with proper lubricant. I suggest not using silicone because it is too light. What you want to use is some good old fashioned grease. Get some Superlube or Molly grease. These will act a good lubricants for metal on metal contact. You must protect these components accordingly because they tend to grind with each other and wear down way too fast.

Hope that helped.

Now here is the fruits of my labour.
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[jordan7831]

Good write up

[e-luder]

Hey jordan, does that Glock look familiar?
That sexy two-tone slide. That well polished outer barrel.
mm mmm mmm.

[jordan7831]

No way! Is that my old glock? I knew it looked familiar haha I loved that thing to bits when I had it. Finish that slide for me an give it some love with some mothers polish! Glad to see its in good hands e-luder!

[e-luder]

Yep. Gave her a nice coat of mother's last night. I love the two tone slide. The black brings out the finish on the breech very nicely. You did an excellent job dude.

[arquloco]

when you say thin, how thin is that? great guide btw

[Americobap1999]

hello, I bought my self a second hand glock 18c with abs slide by ksc, and me gun does not fire on full auto, I don´t lubed it for a long time ago, but I think that the problem is on the screw belloy the sight, I don´t have that scew, did ypu know were can I get one? or ehat is the problem? I put the gun on full auto and then she shot abaut 3 shots and stop shooting, if you like I can send a video by email, thanks