I have been collecting auction & forum post information for Gen2 19's to help narrow down Tupperware boxes and manuals. I wish I could fill in more of the barrel date codes. If anyone has one of the missing Gen2 19 barrel date codes, please message me.CK, that's some awesome info man. I actually was under the impression that only DNs were built before BX serials.
The 3 letters on the barrel represent the barrel date code. In the list I provided above, the first date is the import date (date it was logged into the U.S) & the second date is the barrel date. Typically barrel date is slightly earlier than import date. I think I said all that correctly.