For drilling hardened stainless, I use carbide spade drills. I get them usually from Sheffield Kifemaker's Supply, but Texas Knife Makers and the other Knife making supply companies list them also; as does Brownell's. The only size I've used is 1/8" which run me around $11.00 a piece. They should be run at least around 4500 RPM (I run mine at 7500) with LOTS of cutting oil.