Little FYI:
If you check the firing pin stop edge on the carrier, you can see the amount that the edge hangs over the rounded back edge. If you mic the distance, then chuck the firing pin up in a drill and spin file the retaining lip down to be flush with the carrier lip, it will save you from having to order a new firing pin. Just lightly press the file to the rim, or you stand a chance of bending the firing pin. Or you can just roll file the hammer edge, where it is binding on the firing pin, to solve the problem.
Reducing the firing pin collar is the easiest way to go, plus if the disconnector does let the hammer slip off, the hammer will still be caught in between the firing pin and the back of the carrier. As the carrier bolt move forward, the firing pin will be against the cotter pin with a gap in between it and the carrier. This gap is where the hammer will be retained, and prevent hammer follow threw.