when watching rpm on gun (digital) rpm will fluctuate about 30 rpm

if set @ 800 fluctuates between 780 - 810 normal ? as far as the distributor goes if I buy a new one of the same one I have, should it be good to go without adjusting anything inside distributor.I do not know if anything has changed with them in the 11+ years. I just do not know anything about distributors or anyone around here that I trust to work on it.

thanks