Sierra no longer uses an actual date in their lot numbers. The bottom number (underneath the bar-code) on the white label is the “box” number. Each individual box has its own number.
The longer number on top of the bar code contains the lot number. According to Sierra, the last four characters on the far right of this number are inspection/packaging numbers. The remaining numbers on the left are “barrel” numbers. These barrel numbers are the lot numbers for your bullets.
Sierra used to use the actual date that the bullets were manufactured for the lot number. However, several barrels of the same bullet can be manufactured on the same day/shift. By actually splitting the daily production into barrel numbers, Sierra states that “better control is achieved of the normal exchange of component parts.”