anyone know what lees reasoning is for the rubber washers on the lock rings? thanks

Can't accout for a reason for them. If you use LEEs turret press though they would allow you to set and forget. I aquired extra lock nuts and doubled up the LEE nuts oring to oring with the flat side out, this locks the nuts and gives a solid stop for the dies. I use the LEE nuts on my universal decapper and powder measure mostly.