Specna arms M4 trigger issue

[Wegalaxy]

Hello,

I have a Specna arms m4 with a trigger issue.

When I put the rifle into semi auto and pull the trigger all the way it works.

But when i pull the trigger lightly it bursts into full auto.

I am feeling confident to fix it my self.

Does anyone know what the cause of this problem is just so I have a rough Idea before i open the gear box up.

Thanks 

[ButcherBill]

You might not need to open the gearbox, might be something simply external of the gearbox but hidden within the receiver.

[Wegalaxy]

@ButcherBillis it that little spring that is exposed?

[Skara]

That's the normal mechanical trigger operation, experienced the same "issue" in our rental guns.

What I believe happens is that by pulling the trigger softly and slowly, the gun cycles but the cutoff lever cannot release the trigger trolley, effectively letting off more than one shot per pull, whereas a decise and firm trigger pull will make sure the COL engages the trigger trolley properly.

[ButcherBill]

9 hours ago, Skara said:

That's the normal mechanical trigger operation, experienced the same "issue" in our rental guns.

What I believe happens is that by pulling the trigger softly and slowly, the gun cycles but the cutoff lever cannot release the trigger trolley, effectively letting off more than one shot per pull, whereas a decise and firm trigger pull will make sure the COL engages the trigger trolley properly.

Try this before you get the screwdrivers out.

[Rogerborg]

On 17/06/2025 at 17:49, Wegalaxy said:

when i pull the trigger lightly

 

Don't pull the trigger lightly.

[Wegalaxy]

Turns out one of the contacts were bent. I bent them back into shape and it fixed it. 😁