What do the three-letter designators on the right side of the Steyr pistols mean? For example, my M9-A1 (#035728) has "IOR" as those letters, and my S9 (#021268) has "EOW" as those letters. This is immediately to the right of the "NPv" proofmark.
I spoke with Steyr-Arms today about a few issues. I asked the above question and received an answer.
It is the initials of the person who test fired/Proofed the handgun.
Combined with the proof mark, serial number and initials it can
be possible to figure out the day/date that the gun was tested.