http://www.brownells.com/gunsmith-to...prod20463.aspx
not fancy- and practice with it to get good readings -
use the savings to get the Skeets bore gauge and you have a set to evaluate bores/barrels
PS
I have shown this set before here- I put this together after passing on what may have been a great deal on a hammer gun because the too shinny bores worried me that they had been honed too much
I bought a couple since then, that without knowing the stats I might have passed on-