"perfect is the enemy of good". That line is a good line. It says what is true most of the time.
One thing that takes many years to learn is when to "stop".
Whether it's tightening a bolt or smoothing concrete or arguing.
Aren't you supposed to torque them till they break and then back off 1/2 turn?
The originals were fine thread with castellated nuts with a transverse hole near the end of the bolt for a cotter pin.
I would challenge anyone to find a fine threaded carriage bolt. That just goes against their normal purpose.
