With an extended firing pin and reduced power firing pin spring, when the hammer is down the firing pin will slightly protrude from the breech face.
How do I know, I took a small dowel and inserted it from the muzzle end and made contact with the tip of the firing pin. If I pushed on the dowel towards the breech face I could actually see the hammer move.
So I would assume if a live round was in the chamber and the hammer was down, the firing pin would actually already be in contact with the primer and the hammer not actually bottomed out on the slide like it’s designed. The impact on the hammer would cause the firing pin to hit the primer hard enough to set it off.
With a standard firing pin, the reduced power firing pin spring and a CZC 10lb main spring it will still reliably ignite federal primers, not sure about others since I don’t have any other primer types currently.