Just a thought. Since you changed the firing pin spring and had the same results could the firing pin itself be a tiny bit short? If your firing pin is the correct length then just accept the fact that that ammo is not reliable in your gun. Long story short just don't use it, period. There are too many other good brands of ammo out there. But I do want to commend you for bringing it to our attention. I would think that if Hornady knows it has a problem with light primer strikes, then they should get a new primer supplier. The fact that other brands of ammo works in your gun means Hornady is using very tempermental primers that do not allow for any variance from "standard". That is simply not acceptable in a product marketed as Critical Defense ammo. Critical Defense should imply that it would work in a zip gun with a firing pin powered by a rubber band.