I recently put the sitting fox stamp on the rust blued Davis lock on a NW trade gun I built. It was an after-thought of the owner and I cautioned him that there might be some damage to the finish. Aside from letter stamps, it was my first stamping experience and I learned two things:
First - practice and then practice some more before tackling the parts. I tried multiple hits on 1075, including straight-on and angling into it and found it impossible to completely avoid some misalignment. For me, a single strike was the answer and the required weight of the hammer was surprising. I started with a good swing on a 12 ounce hammer and didn't get consistently good results until I had graduated to a hammer weighing about 2 pounds. You also need the part sitting on good solid surface having some mass. I used a small anvil. In my experience, a bouncy work bench won't cut it.
Second - there was very little damage to the finish and what damage there was was limited to the bottom of the imprint.
Being the cautious type, I declined to stamp the barrel.
Thanks HH, I was unaware the red fox is an introduced species.