How do i take a value from an ending value from a field and use it as a starting value the next time i open a record?

How do i take a value from an ending value from a field and use it as a starting value the next time i open a record?

Yes, i want the ending volume of the previous record to be the beginning volume of the next record.

i have also provided edit access.

in our winery every action starts with a beginning volume (bvolume) and ends with an ending volume (evolume).  

by way of example:
Chardonnay beginning volume = 1000 gallons
chardonnay filtered
Chardonnay ending volume = 980 gallons

The next time i open this field, i would like the beginning volume to show the ending volume (980 gallons) from the last action.  

Can anyone help?