From: 7/16″ is for stainless steel inserts 31/64 is for brass inserts
The 5/16″ and 11/32″ stub drill bits have a 1 3/4″ flute length and the total length is 3 1/16″. The standard wood bit is longer and tends to “wander” if it hits a tight wood grain.
The 5/16″ is the most common drill size for threading a 3/8″ x 16tpi hole. The 11/3