Technically speaking, you want to measure with the inside of the jaws when possible because the farther you get from the "main beam" ( the part where the two jaws are connected) the more chance there is for slop in the connection to play a role in measurement differences.
practically speaking, with most stainless steal dial calipers, the is no difference ;)
you should pay more attention to the amount of pressure you put on the caliper when taking a reading.
I used to re-load but now I "hand-load".
-- Well, at least I try