The primer strikes are lite on the first strike, and sometimes they will fire on the second try... if they don't fire, the primer strike is deep after three tries.
I'll assume with that statement your fully depressing the AT blade?

Discounting ,first of all I'd set the firing pin protrusion to .030"-.035" and then set/reset the overall pin assembly length.

Second I'd make sure the sear moves freely and the trigger over travel isn't set too tight, it needs a bit of over travel or its going to drag on the trigger after its released padding the pin fall.

Just a few things I do or check at this point to start.

Bill