I have noticed that the regular $1.00 Washington dollars are a tiny bit smaller than the ones without the edge lettering , why would this be ? Has anyone else noyiced this?
One possibility is that the edge lettering machine slightly reduces the diameter of the coins when it squeezes them, so the ones that miss that machine will be a tiny bit larger. Have you managed to measure the two varieities?
It requires a sideways pressure on the coin as it rolls through the lettering dies. This compresses the coin slightly.