Darren,
Flatting off the first thread at the point where is becomes "full profile" (beyond any leading chamfer) is called a "Higbee". I have no idea what or who that actual name or term relates to, but it's commonly used in armament breeches to afford positive engagement of two mating threads. A normal Higbee start would be blunt. On mine I tried to make it a little positive and sharp so it would act almost as a tap.
If yours is more like mine someone may have tried to do just as I did. Why, I have no clue. You should smooth it out if it's sharp.
Flatting off the first thread at the point where is becomes "full profile" (beyond any leading chamfer) is called a "Higbee". I have no idea what or who that actual name or term relates to, but it's commonly used in armament breeches to afford positive engagement of two mating threads. A normal Higbee start would be blunt. On mine I tried to make it a little positive and sharp so it would act almost as a tap.
If yours is more like mine someone may have tried to do just as I did. Why, I have no clue. You should smooth it out if it's sharp.