Perma Fin is tough, but it ain't perfect. Just like bluing, it can be scratched. Take a look at the top of the hammer, just in front (to the right, in the photo) of the serrations. See the little shiny spot? That's bare steel, where the Perma Fin has been scraped off of the hammer.
When the lever is operated on a Model 94, the bolt moves rearward and cocks the hammer. It does so by shoving against the hammer's front surface, and as the bolt continues to move backward, the hammer rides against the bottom of the bolt under spring tension. The bolt thus slides across the top of the hammer, wearing heavily on it.
It's completely natural to expect any finish to wear rapidly under such treatment, and Perma Fin is no exception. This is not a complaint by any means, just a wake-up call to anyone who may be under the impression that Perma Fin is completely impervious to damage.
Like any kind of bluing (including factory finishes), Birchwood-Casey Perma Fin can be scratched, gouged, scraped, and abraded.
As I said, Perma Fin ain't perfect... but it is mighty tough stuff, and it's a good do-it-yourself solution for any gun that's badly in need of refinishing.