Normally, you would drill with a 23/64 drill, and follow with a 3/8" reamer. The 6 flute reamer is much more accurate than a 2 flute drill bit. If you have ever closely watched a 2 flute drill, it creates a hole with 3 wallows in the hole, by it's nature. The 6 flutes of a reamer remains centered for a near perfectly round hole. Of course, if you only have a 3/8" drill bit, you can get by with that.