I also use masonry bits to drill even in HSS. You can grind a little negative rake on the cutting edge to help. The big concern is to not let the drill get too hot,or the brazed bit will melt in the seam. I generally run the bits pretty fast,but haven't had to drill a 1/2" hole that way. Usually 1/4" or smaller. You need to buy a few extra bits and experiment with speed. Also,resharpen the bit for every few holes if you have a diamond grinder. I was drilling solid HSS old power hacksaw blades to make knives from,and found that I needed to keep the bits sharp,or they would burst the blade in half. These were solid HSS all the way across,not just welded on HSS teeth.