Ok, you're not actually going to get any help from those Confederacy bods anyway, because Firkin is not a "deep south" word its an old English one...

A "firkin" is a unit of measure used in English Pubs -
"A firkin is a small beer cask, holding nine Imperial gallons (72 pints). The name is derived from Dutch (vierde meaning four). Two firkins make a kilderkin, two kilderkins make a barrel and one-and-a-half barrels make a hogshead of 48 gallons (384 pints). Aluminium kegs start at nine gallons."

Hope this helps...