Problem with trigger/cutoff/selector

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So this has been driving me crazy for a while and I can't figure it out.

So my buddies gun shoots semi on semi, and auto when the selector is auto. The issue I'm having is the trigger pull. Safety works and auto works. When I fire semi, there's resistance. Like something is in the way. But I can pull it with a little added pressure and it will snap like a nerf gun (spring) sound and then fire semi.

I want to get rid of this. Originally I thought it was the safety lever not moving enough to let the trigger pull fully, but after troubleshooting by removing the cutoff lever spring that moves the lever from the selector, the problem goes away.

So when the cutoff lever is engaging for semi, I think it's getting in the way of the trigger connector trolly or something like that.

Has anyone ever experienced anything like this? I feel like a tiny bit of filing is in order some place maybe?

[Spike]

What kind of gun is it? Any of the trigger mech aftermarket?

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Trigger mech is CYMA. I believe i solved it. There's an abnormality in the trolly that is messing with the cutoff lever. I replaced it with an SHS aftermarket one and no more trigger issues. BAH!