Rob;
I would guess the CL of the lens was a little to the rear of the breech face. You can see just a nub of the firing pin. It does not however have it's full protrusion as if the hammer were actually resting upon it under spring tension. Early models had two screws in the frame bottom which set the point where the spring stopped. Later ones are not adjustable, but all I have dealt with allowed the pins to come flush or just beyond. "NONE" have ever been plagued with firing pin drag upon opening.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra