The magic art for drilling holes in spring steel consists of using an ordinary masonry drill bit (i.e. brazed-on carbide tip, which is always sharpened with negative rake), running the drill pretty fast, and keeping the cutting edge submerged in oil. It chews rather than drills, and is therefore quite slow. Don't let the pool of oil go away, or the tip will immediately heat up and melt the braze joint holding the carbide tip to the SAE1040 drill bit.
It works because of the negative top rake of the carbide tip, which prevents digging in and developing high torque on the drill bit. The carbide stands up pretty well - I've drilled 3/16" holes in two pieces of 3/4" diameter spring steel bar without resharpening along the way, though I had to sharpen it after finishing the pair of them.
I hasten to disclose I didn't invent this, it's a standard trick of the trade in small machine shops.
