I tried installing a new PSA FCG in a GF3 barreled action. The hammer won't lock back when cycling the bolt, and the disconnector won't catch the hammer with the trigger pulled back either.

I removed a known good FCG from my WASR-10 to install in my GF3 for troubleshooting, and it did the same thing. At that point I thought that the problem was with the GF3, but I tried installing both FCGs in my WASR-10 and now it has the same problem.

The only part that is common between these two rifles is the new pin retaining plate. I have not been able to reinstall the pin retaining spring from the WASR in either rifle. Where do I go from here?

You remember to instal the disconnector spring?

The disconnector springs are installed in both. I'll get some pictures posted soon.

The trigger and the slot in the bottom of the receiver have to match in design.

The early style has two short slots for the early design trigger.

The later style has one longer slot for the later style hammer.

American triggers have been made for both styles in a mix of single hook and double hook triggers.

If the short double slots are too short for the trigger design, the trigger might not release the hamer.

If the slot in the receiver is too long for the short hook trigger, the trigger will over rotate and the disconnector can not catch hammer to reset it.

It sounds like the slot on the bottom of the receiver is long.

This requires a long hook trigger.

A full auto rate reducer can help limit the trigger by acting as a trigger over travel limiter.

In trying to reinstall everything for the pictures, I think that I have been installing the hammers backwards. F*** me if I can figure out how to orient the spring though. AR FCGs have spoiled me....

Update: It was backwards hammers this whole time. Three days of trying, walking away, and trying again, just for backwards hammers. At least they both functionally check out good now.

Ouch, glad you figured it out

Thanks! I am too. That was really starting to get to me.

For some reason I had it in my mind that the rounded bar on the top of the hammer is what hits the firing pin. When I put everything back in to take a picture, I noticed that the rounded part on top sits too high to do that. Lightbulb moment....