I had a few left over white hex 8 x 1/2" self-tapping screws from the new aluminum gutter install but I needed a few more. I have been to home depot and several big hardware stores but can only find them online. (See attached photo) There are apparently various types of self-tapping screws, but from I gather I shouldn't be using the ones that have that special look at the point. The ones in the photo have very sharp edges and were very easy to install. My leaders are aluminum and I assume the screws should be aluminum too, though they seem to be hard to find. One store sold me some stainless steel phillips head 8x 1/2" as a backup but don't know about the interaction between aluminum and stainless steel. Any thoughts?