You still have to wonder why the safety notch wasn't machined long enough for the hammer to catch . . . why "half machine" a part?
As a follow up to my earlier post - my Piettas are machined correctly and the hammer catches. When I'm shooting at a range situation, I don't utilize the safety notches. If I'm going to carry in a holster as in a hike, I have the hammer resting on an empty chamber. That was the way I was taught 50+ years ago in regards to revolvers and old habits die hard. I even do it on my "newer" SA cartridge revolvers regardless of cross bar safeties, etc. The only revolver that I don't do that with is my Ruger LCR 357 CCW which is DA only and designed to be carried fully loaded in all five chambers.
If a pair of '51 Navies were good enough for Billy Hickok, then a single Navy on my right hip is good enough for me . . . besides . . . I'm probably only half as good as he was anyways. Hiram's Rangers Badge #63