[John Sabato]

If cycling a misfired round through the loading sequence gets it to fire the second time around then there is do doubt that the firing pis is striking the case primer. The issue that your masking tape test does not address is whether or not the momentum and depth of the strike is adequate.

The only way you can adequately test this would be to trade firing pins with a reliable shooter Luger and see if it makes a difference. If it does not, then try swapping the firing pin springs and test.

If the gun is now reliable then you have found your problem. The problem will likely also appear in the gun you borrowed the parts from. Let's us know how it goes when you test.