In addition to Rick's comments, I would add ...
Define "between". Do you mean with a date/time field value between your two
records' values? Or between two "numbering" record values? As Rick points
out, you can't "insert" an Autonumber between 00001 and 00002.
And if you are using the Autonumber field as designed, you would NOT want to
"bump" the 00002 record (and every record above it) up by one to insert a
new record -- that could potential mess with any "child" records you had in
There would be no reason you couldn't keep your Autonumber ID field, and add
a "sequence/sort" number field like Rick mentioned.