Miller,
The Skeet's I have, an older one, the needle travels both +/- and will travel .500 in length.
I had explained what you had said to Greg about re-zeroing once you found out what bore size is and then setting to zero and read choke which would be reading in minus readings now (unless bored out).
I find this easier to read than leaving dial set at the ring (.700) reading bore and then subtracting as it is coming out from choke area. Much easier to re-set to zero inside of bore and then read choke area. JMHO
