Trigger spring kit for FN509

Just finished installing the trigger spring kit. Had to change back to the factory striker spring because I was getting light primer strikes and FTF’s. Changing back to factory spring solved the problem. Trigger is much better although not as good as the factory trigger in my Walther PDP full size. Also I noticed on the install video - on the sear spring install - the right hand bend on one leg of the spring is supposed to be installed in the small hole on the sear and the straight end rests on the bottom of the sear. The video shows the opposite. Maybe it does not matter? Just thought I would mention it and was wondering if anyone noticed this??


Yes I noticed this. It is an error in the video. You got it right. And are you using the Apex striker? Because that is the only way that light strikes occur with the trigger spring kit. The Apex striker is nearly twice the weight of the OEM striker. FN designed a lightweight one for a reason.

I appreciate the quick reply. You guys have great customer service.

I have the factory striker. The pistol is factory stock the only addition being a Holosun red dot. It is the LS EDGE model of the FN509. Never had any issues with FTF’s or light primer strikes. I installed the spring kit because I hated the stock trigger (gritty and spongy). The spring kit improved trigger feel quite a bit. Changing back to the factory “red” striker spring solved the problem of light strikes. There was 1000 or so rounds fired before the installation, mostly being reloads, Winchester “white box” and some Federal and Remington factory loads. Never missed a beat. I have no problem using the factory spring. Trigger still feels better than before. I wasn’t complaining about the MCARBO kit, just wondering anyone else had issues? Could it be that the LS has a longer slide or something else? Wasn’t sure if I did something wrong with the installation.

Would appreciate your thoughts on this.

Thank you,

Bob Turner

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