Lot numbers are assigned when ammunition is manufactured. The lot number identifies an item constructed
according to pertinent specifications. It is an essential part of the markings, and is required for record keeping
purposes, for preparing reports on the serviceability and functioning of the ammunition, and for reporting
accidents in which the ammunition is involved.
There are two lot numbering systems currently found in the ammunition inventory. The older system is being
phased out, but it may still be found on items in storage.
The Old Lot Numbering System. This system consists of a manufacturer's identification code, an interfix
code, a sequence number, and (in some cases) a lot suffix code. The manufacturer's code is a two-digit code
assigned to indicate the specific location of manufacture. The interfix number identifies lots produced by the
same manufacturer at the same time and location. The sequence number identifies lots in a specific interfix
series according to production sequence. A lot suffix may be added to denote a rework effecting a material
change in the original lot. For example, the first rework is identified by the suffix "A," the second rework by a "B,"
and so forth. A breakdown of lot number LW-06-01A in the old system is given in Table 1-1.
Table 1-1. Lot numbering (old system).
The New Lot Numbering System. The new lot numbering system is described in MIL-STD 1168A. It
consists of a manufacturer's identification code, the year of production, the month of the production run, an interfix
number, a sequence number, and (in some cases) a lot suffix. The manufacturer's codes are combinations of
one, two, or three letters that indicate the specific location of manufacture. The year of production consists of the
last two digits of the year in which the ammunition was manufactured. The month of production code is a single
letter (A through M, excluding I) identifying the month in which the ammunition was produced. The interfix code is
a three-digit number. It identifies lots of ammunition produced by the same manufacturer at the same time and
location. The sequence number is a three-digit number. It identifies ammunition lots within an interfix series
according to production sequence. The lot suffix indicates the number of times an item has received a major
rework. This new lot numbering system functions much better than the old system to identify ammunition should
a defect occur. A breakdown of lot number LOW 91M 006-001B in the new system is given in Table 1-2.