dale,
the quater rib is nothing more than 1/2 X 1/2 inch square stock from the local hardware store cut and shaped. The stuff comes with cadmium plating but that's easily filed and polished off. It's a mild steel and blues very well. The riser for the front base is of the same material in 3/8 inch.

While I'm glad some have found the rust bluing description helpful please do not take it as some sort of tutorial!!! For heaven's sake it was my FIRST attempt. That said, I found it rather simple though time consuming. The results are pleasing though and well worth the long, dirty job! I'd reccomend it to anyone wishing to try their hand. In fact I'm just in from putting the first coat of solution on the parts of a 20bore gun I decided to do today because of the high humidity.