I rechecked things a bit more last night. The hammer is hitting the striker at the point where the hammer just begins to radius back at the top rather than hitting the flat face of the hammer. It's right at that transition. I may need to reshape the face of the hammer a bit or adding metal to the top of it to build up a flatter face. Trimming the striker back more at this point will allow the hammer to swing further forward, but that would also result in it contacting the hammer closer to its top. In short, my hammer sits just a smidgen too low.
I have a few spare hammers I can check to see if one will work better than the one I currently have installed. These are all foreign made FCG parts I'm tinkering with at this point. Once I'm done debugging I'll modify a US made set to satisfy the parts count gestapo.