Ok, to answer some questions:
This is brown box ammo, packaged almost like Federal XM-193, save for lighter color boxes, contained within a wood crate that looked to hold 1000 or more rounds. The headstamp was 93. The Brass was annealed, and bright and shiney, showing no corrosion or other faults [in the box I opened]. If I can find the place again [see below], I will buy some and do an ammo review. The guy behind the counter didn't have any info about if it was new surplus, or what it was...
I found it in a little gunshop I drove past in southern IL. I am currently kicking myself for not making notes exactly where, but it was somewhere between Carbondale and Evansville IN. I normally just stop at any gunshop or pawnshop I find, just on principle and to stretch my legs, so I don't usually pay much attention to where I am at unless there is something really spectacular about the shop.