Runout = wobble when you spin the arrow. I think most replaceable blade b-heads come w/ washers. i doubt very much that you could go to a hdwe store and buy the right size, as these appear to be machined.

Randy, aka 10 pt can take an arrow between his palms and spin that sucker like a top for a loonnnggg time! While it's spinning you eyeball the head to see if there's any wobble. You don't need to go to the lengths I do on anything, lol, I'm anal retentive on stuff like this. If I can't get my rifles to one hole at 100 yds, they go to the next gun show and I fall in love w/ something else.