I finally took a piece, did a diagonal grind over 2" of the length, and etched, just to make sure that it wasn't the steel.
The etch came out blotchy, with clear boundries indicating where one alloy started and another ended. There were patches nearly white, and others black.
Whatever this was, it wasn't 1050. I called up my supplier and offered to send them the piece to prove that I hadn't gotten what I had ordered. They declined, apologized, and are shipping me a new order free of charge. Apparenty this happens frequently, someone mis-marking a piece of steel and sending it out. Bah. I had them change the alloy to 1075, too, as that's a bit harder to mistake.
I'm guessing this is structual steel, A36 or some other steel that only needs to meet a strengh specification instead of an alloy specification such as 1050. Bah, 2 months down the toilet. Good thing I'm not a professional, this could have really hurt me if I had a deadline.
Steel should be here next week, hopefully before the 3 day weekend. I'm looking forward to it.