Forgot to mention. Steady hands
Derringer is easier because you can use the screw hole as a guide from the top. Just remove the grub screws or Phillips head screws from the center post and wrap the base in the paper towel to prevent scratches gripping the edges with your adjustable pliers.
Place the#60 bit in the Dremel. Be sure to tighten beyond hand tightening so the bit doesn't travel. Find a comfortable position, turn the Dremel on its LOWEST speed and start.
Let the bit do it's job. With SS you do have to apply more pressure which is why bits break more often.

Derringer is easier because you can use the screw hole as a guide from the top. Just remove the grub screws or Phillips head screws from the center post and wrap the base in the paper towel to prevent scratches gripping the edges with your adjustable pliers.

Place the#60 bit in the Dremel. Be sure to tighten beyond hand tightening so the bit doesn't travel. Find a comfortable position, turn the Dremel on its LOWEST speed and start.

Let the bit do it's job. With SS you do have to apply more pressure which is why bits break more often.