The reamers are turned down to shape in the lathe, then almost 1/2 is ground away to form a "D." This D-reamer is then hardened and the small amount remaining is ground to exactly 1/2 the original diameter. These are called D-reamers because in cross-section they look like a D. The final fine-grinding and honing may be done by hand and forms two cutting edges at the points of the D.
The die is rough-formed in the lathe and finished with this D-reamer. They are often used in developmental work. Of course, full-fluted reamers are then custom ground if the prototypes is successful. The cutting process with a D-reamer is slow, but it works. A pilot for the reamer is usually necessary because the forces involved in the cutting are unbalanced, unlike a multiple-flute reamer.
Incidentally, I know personally of someone who shall be nameless, but is not me, who accidentally and unknowingly used a solid silver spoon (from "Grandma," who shall also remain nameless) to stir his pot of bullet alloy.
This was told to me as solid unalloyed truth and I believe the party who told me.
He made the interesting discovery that silver is dissolved by molten lead when he left the spoon in the pot for a while. He did cast bullets with this silver alloy. I have no idea of the resulting percentage of silver in the alloy, or for that matter what the minimum percentage of silver is for one shot kills on zombies or vampires or werewolves or whatever.
However I would assume that an arrow or a bolt from a crossbow would be functionally identical to a wooden stake, and can be administered remotely, just like silver bullets.
Terry, 230RN