light primer strikes

[LCFD#22]

I built a lower recently with a JP trigger #JPFC-1. JP recommended that I trim my hammer. So, I did would this cause light primer strikes? I shot around 30 rounds today and had 4 miss fires due light strikes. I reload the ammo and they did fire. So, it wasn't the primers. One actually didn't even have a dimple on it. I have another hammer I can take out of my DPMS and try it if I have to. Just wondering what thoughts or experiences others have had. Thanks

[WantBigBoom]

Do you have all your FCG springs installed correctly? A reversed hammer spring will cause weak strikes.

[JoeBob]

What he said ^^^. Verify the springs are in correctly.

Have you function tested it?

[LCFD#22]

Yes, the springs are in correctly. I'll tear it down tomorrow just to make sure once again. It would be worth the time just in case I was wrong.
I function tested several times.
Thanks for the thoughts.

[WantBigBoom]

No need to tear down, just post a picture of the FCG with the hammer up and down, somebody will be able to spot if a spring is upside down for you.

[John A.]

The JP hammer springs are considerably lighter than an OEM hammer spring.

They will very often cause light strikes, especially on harder primers like what you'll find in surplus import ammo, and even #41 5.56 primers.

I used reduced power JP springs in my AR builds and recently have had to replace one of them due to light strikes.

It also may not be a bad idea to take the bolt apart and make sure there isn't a lot of fouling in the channel where the firing pin goes through either.

I don't know about anyone else, but I also store all of my weapons with the hammer released to eliminate undue prolonged tension on the springs.

I know it's been a hot button topic about springs taking a set, but I feel better doing it that way, so that's how I do it. As always, ymmv, take it fwiw, etc.