ICS-128 Incorrectly shoots in full auto after depressing forward assist knob

[Cokeman]

I have a 2011 ICS M4 gun (ICS-128 S.I.R. Crane Stock) that incorrectly shoots in full auto (when in semi fire mode) after the forward assist knob has been depressed (to release the spring tension).

Here is a video showing the problem (YouTube - 2011-03-06 - ICS-128 FIring Problem). In case the video is not available, it shows:

1. Gun shooting correctly in both semi and auto fire modes
2. The forward assist knob is depressed
3. Gun is in Semi fire mode. Trigger is pulled and the gun shoots a burst in full auto.
4. Pulling the trigger again, it shoots in semi mode.
5. Gun shoots correctly in both semi and full auto mode.

This problem is 90% repeatable.

I did search through ASC and came across this thread/solution (SOLVED ICS M4 firing full auto and bursts on Semi-Auto). His solution was to ensure that the forward assist lever was moving smoothly. I checked and mine is moving smoothly.

So, does anybody have any ideas what is causing this problem and a fix?

[Sportco]

Well...

I had something sort of similar...
The trigger would lock up and sometimes fire full auto on semi mode after using the spring release... I realized that the plastic cam system (front left side near contact) in the lower gearbox would play lateraly and cause this...

I found the problem to be the rear of the front top spring had slipped towards the right side..

The solution was to reposition the front spring by pushing the rear of it towards the left

Stopped doing it! (was expecting to have to immobilize it never had to... never did it again!)

Hope it helps... Good luck!?!

Cheers

[Cokeman]

Originally Posted by Sportco

Well...

I had something sort of similar...
The trigger would lock up and sometimes fire full auto on semi mode after using the spring release... I realized that the plastic cam system (front left side near contact) in the lower gearbox would play lateraly and cause this...

I found the problem to be the rear of the front top spring had slipped towards the right side..

The solution was to reposition the front spring by pushing the rear of it towards the left

Stopped doing it! (was expecting to have to immobilize it never had to... never did it again!)

Hope it helps... Good luck!?!

Cheers

Are you talking about the spring in the attached picture (the one above the gears)? I tried moving the lower part of the spring over to the left . However, it easily moves back over to the right left (picture shows the spring as far over to the left as I can move it).

The first time I did it, I think I got the desired behaviour, with the first trigger pull (on semi) not actually firing the gun...it just sounded like all the gears moving into positon. The second trigger pull performed a correct semi fire. A few cycles of depressing the forward assist knob/firing returned it to the previous behaviour, so I guess the spring slipped over to the right. I guess the only option is for me to immobolize the spring. One idea is to use a dremmel (or small file) and cut a little groove into the post, forcing the spring to remain in position.

However, I'll wait until you confirm that this is the spring you were talking about before I cut a groove.

Thanks

[Sportco]

Yes that is the spring and what you descrived is what I was expecting when I did it... but for some unknown reason mine never moved back out of place...

Because this is a poor quality metal casting, I wouldnt risk a dremel on it, if it were to break... that would be an unpleasant situation

Just an idea... Since you might have to fine tune the spring position, why dont you put something like a coat of silicone adesive or 5 minute epoxy on the bar let it cure, then seat the spring without damaging it... because both these stuffs are flexible, the spring will digg in and lateral slip will probably be eliminated

or better yet... wedge the spring between two tight o-rings so you can reposition need there be

Cheers... glad it worked!

[Gadoury]

Don't want to hijack your thread but, are those depressing knobs only wrking with gbb air guns?!? On my aeg, this knob kind of look only as a decoration.

[Sportco]

Originally Posted by Gadoury

Don't want to hijack your thread but, are those depressing knobs only wrking with gbb air guns?!? On my aeg, this knob kind of look only as a decoration.

No problem... that is a good question...

That my friend is because you have an SRC... and that is only true for SOME ICS models... and another brand that doesnt sale anymore

The ICS M4 and MX5 has a split gearbox system ((great system for people who like to do maintenance on their AEG)) the upper has the spring, piston, head and nosel; the lower has the mechbox (motor, gears and electric switch)

On an ICS split gearbox you can for example replace the complete upper gearbox in about 9 secondes.. so instead of having two AEG (one for inside at 340FPS and one for outside at 395fps we just have two upper gearbox and switch them arround according to need ((cost is about 80$))


A complete dissasembly/reassembly for the upper gearbox takes about 10 minutes... and of course if you have a problem with the lower you can split the system and actually SEE it work to understand what is wrong

But separating the two half while under tension would potentially damage things... so the rachet knob releases the spring tension before you split the two halfs

Cheers

Ps that picture you see is a vertical view of the lower gearbox... so Cokeman got to work on the problem without even dismentalling is AEG... and that my friend is priceless!

[Gadoury]

Yeah thanks, my problem is when i shoot full auto and my battery dies with otu shooting and i know my spring is compressed. Then asap i charge my battery and shoot in semi so the spring can release and removed tension that otherwise would be kept untill the next shooting period! The release knob assist woukd be nice in those situations. Thanks.

[Cokeman]

Originally Posted by Sportco

Yes that is the spring and what you descrived is what I was expecting when I did it... but for some unknown reason mine never moved back out of place...

Because this is a poor quality metal casting, I wouldnt risk a dremel on it, if it were to break... that would be an unpleasant situation

Just an idea... Since you might have to fine tune the spring position, why dont you put something like a coat of silicone adesive or 5 minute epoxy on the bar let it cure, then seat the spring without damaging it... because both these stuffs are flexible, the spring will digg in and lateral slip will probably be eliminated

or better yet... wedge the spring between two tight o-rings so you can reposition need there be

Cheers... glad it worked!

Thanks for the suggestions I'll check with Canadian tire to see if they have silicone adhesive or 5 mintue epoxy.

[Cokeman]

Originally Posted by Sportco

Yes that is the spring and what you descrived is what I was expecting when I did it... but for some unknown reason mine never moved back out of place...

Because this is a poor quality metal casting, I wouldnt risk a dremel on it, if it were to break... that would be an unpleasant situation

Just an idea... Since you might have to fine tune the spring position, why dont you put something like a coat of silicone adesive or 5 minute epoxy on the bar let it cure, then seat the spring without damaging it... because both these stuffs are flexible, the spring will digg in and lateral slip will probably be eliminated

or better yet... wedge the spring between two tight o-rings so you can reposition need there be

Cheers... glad it worked!

Before I made any semi-permanant fix, I decided to try a temporary fix first. So, I wrapped the little bar with electrical tape to give the spring something to grip. I was able to position the spring way over to the left. However, now it doesn't seem to make any difference. I still get a burst of full auto (sometimes multiple full auto bursts) before the gun settles into firing correctly in semi-automatic mode.

So, it seems that I'm back to square one.

[Lumi]

Look at the pictures attached, I've circled the cut-off lever end in red. After using the forward assist and before firing the gun crack it open and look at this lever end, with the gun open and the battery out put the gun to Semi and squeeze the trigger, does the white plastic piece go over or under the metal tab on the cut-off lever? It may be that the gears are pushing on this after they reverse and lifting it just enough to be switching it to full auto for the first shot.
How it might look
How it should look

I'm still trying to figure out how to correct this if that is the problem, but if it is we've at least got it narrowed down.

[Kos-Mos]

Originally Posted by Lumi

Look at the pictures attached, I've circled the selector lever end in red. After using the forward assist and before firing the gun crack it open and look at this lever end, with the gun open and the battery out put the gun to Semi and squeeze the trigger, does the white plastic piece go over or under the metal tab on the selector lever? It may be that the gears are pushing on this after they reverse and lifting it just enough to be switching it to full auto for the first shot.
How it might look
How it should look

I'm still trying to figure out how to correct this if that is the problem, but if it is we've at least got it narrowed down.

DING DING DING!

That is the reason why it would cause your issue.
Happens to most ICS rifles that are properly adjusted.
Thge trick is to remove half a millimeter off the trigger block (the part that moves) to let the cut-off lever fall down as it should.

[Lumi]

@ Kos-Mos
I'm not seeing where you would remove the material from, what I've noticed on my gun is that the gears are stopping just after they've started pushing on the lever and they're lifting it and holding it up, the lever can't drop back down because the spur on the sector gear is pushing it instead of being stopped dead by hitting the lever as it reverses.

[Cokeman]

Originally Posted by Lumi

Look at the pictures attached, I've circled the selector lever end in red. After using the forward assist and before firing the gun crack it open and look at this lever end, with the gun open and the battery out put the gun to Semi and squeeze the trigger, does the white plastic piece go over or under the metal tab on the selector lever? It may be that the gears are pushing on this after they reverse and lifting it just enough to be switching it to full auto for the first shot.
How it might look
How it should look

I'm still trying to figure out how to correct this if that is the problem, but if it is we've at least got it narrowed down.

When I pull the trigger, in semi mode, the plastic piece goes over the metal piece.

However, I think my problem doesn't have anything to do with the forward assist know. Today, when I am in semi-auto mode, it will fire on full auto about 75% of the time.

[Cokeman]

Originally Posted by Lumi

Look at the pictures attached, I've circled the selector lever end in red. After using the forward assist and before firing the gun crack it open and look at this lever end, with the gun open and the battery out put the gun to Semi and squeeze the trigger, does the white plastic piece go over or under the metal tab on the selector lever? It may be that the gears are pushing on this after they reverse and lifting it just enough to be switching it to full auto for the first shot.
How it might look
How it should look

I'm still trying to figure out how to correct this if that is the problem, but if it is we've at least got it narrowed down.

Originally Posted by Cokeman

When I pull the trigger, in semi mode, the plastic piece goes over the metal piece.

However, I think my problem doesn't have anything to do with the forward assist know. Today, when I am in semi-auto mode, it will fire on full auto about 75% of the time.

With Lumi's pictures and description, I believe that I've isolated my problem (in semi-auto mode, gun would fire full auto 75% of the time) and a identified a solution (in the process, I disassembled the lower gearbox and was able to understand how it works). When in the semi-auto fire mode, the cut-off lever is in the lower position, so that when you pull the trigger, there is a plastic piece on the switch assemble that moves forward, on top of the front tab of the cut-off lever (as shown in Lumi's picture, I've attached a copy of the picture below, so that it will always be available). With the cut-off lever held down, the gears will only spin once to fire a single shot. However, I noticed that on my gun, the metal contacts in the switch assemble would establish a contact before the plastic piece went overtop the cut-off lever. As the gears spin around, the cut-off lever would get flipped upwards with each rotation of the sector gear (the gear that you can see in the picture) and the gun ends up firing in full auto mode.

So, I fixed my problem by making sure that the fire mode selector was operating the cut-off lever correctly. Then I spread the contacts (in the switch assembly, the contacts are beneath the spring shown in the picture) so that it required a longer trigger pull. This gave the plastic piece enough time to get ontop of the cut-off lever, thereby enabling semi-auto firing.

What a relief!!!!! It really sucks paying so much money for a new AEG and then getting a major problem (and a few minor ones as well) and you are essentially on your own (with the great help from ASC members) to resolve it.

Thanks everybody. Much appreciate it.

However, I still have the original problem with the gun firing a full-auto burst (fire selector is on semi-auto) after depressing the forward assist knob. I guess it is related my problem/solution for why my gun was shooting full auto when in semi-auto mode. But I just can't figure it our right now.

[Kos-Mos]

In the picture with the cut-off lever in the right position, the plastic part that ride over it. The front section is sometimes just long enough to prevent the cut-off lever from dropping down after the shot. That makes it useless to cut the fire when in semi.

Since that part is molded, sometimes the mold is not perfect and that part is stretched too far forward. Removing the sharp front edge usually solves the issue and does not changed the function of semi or auto.