Thanks GT for the explanation along with the pictures.

Thank you for this post. Clear, complete and valuable information.

Kevin B.

I used this infornation for a tang sight on Saturday and it worked very well. It made a lot cleaner lines than trying to use a rotary type tool.

The method I use and described here works quite well and is fairly simple but I have found a few flaws that I'd like to point out.  In the first picture I'm attaching, the tool I made for marking the lines in the sight block was from a used carbide insert, silver brazed to a bar and the tip was ground to a fine point. If you look closely, the lines were cut from left to right.  As I proceeded the marking process one can see the tip is breaking down rapidly - it was a short distance, few marks, but it was A2 tool steel- carbide cuts the harder material but it doesn't like being "dragged" back through the cut - the tip breaks off.  Resharpening isn't a problem, but with old eyes, picking up location and resuming is a real challenge.  The staff in this picture was from mild steel and the markings were cut using a piece of HSS silver brazed to a steel shank and then sharpened, it held up fine and produced decent markings.
The second picture if you look close was a staff from Damascus that I had to regrind the tool several times and my markings aren't what one really likes to see.  The Damascus took it's toll on the number stamps too so for these markings I used a diamond scribe, not real appealing either but functional for my rifle. 
In most of my sight markings, I use HSS material and have had good results.  I have tried my pantograph engraver, the etch-o-matic, and a rotary engraver in the mill for marking the lines.  I've seen the results of the laser engraved markings and they don't inspire me to go this route.
The last two pictures are marked with a cobbled up tool using HSS tool bit scraps.
Greg