[villagetinker]

Here is another suggestion.

I am assuming that you are using concrete bits for the stucco, these in general will not cut through metal. Get a COBALT bit the correct size, and use it JUST FOR GETTING THROUGH THE METAL, then go back to the concrete bit if you need to go deeper. Cobalt bits will go through just about any metal. I know the ACE hardware's carry these bits.

CAUTION: If you use the cobalt bits on the concrete you will ruin them, then you will be asking me to sharpen them, as I have a drill bit sharpener.

Hope this helps.