Here's Wikipedia's definition of drill fabric.
"Drill is stout durable cotton fabric with a strong bias (diagonal) in the weave"
It does not specify a specific weight of fabric, just the kind of weave and later in the article, it says that light weight drill is used to make clothing while the heavy drill is used in such things as boat sails, awnings, tarps, etc. I have found that the weight of drill that I use is often used to make pockets because of its durability. I have told some people about it and when they went to the fabric store and asked for "pocket drill" the clerk didn't know what they were talking about. To the best of my knowledge, all full line fabric shops carry it but may call it by a different name. Of course, it is also highly likely that the clerk to which this person talked just didn't know their fabrics and didn't know what was being asked for. Since I know exactly what I am looking for, I just ask for cotton drill, I look for the weight that I want and then I whip out my micrometer and start measuring. I have bought that fabric from several different shops and have never failed to find the weight of cotton drill that I want. I was originally told that the fabric was called "pocket drill". Maybe it is and maybe that was just a local term for it. I don't know. I just know it is a light weight cotton drill with a nice tight durable weave. 'Tain't hard to find once you know what to look for even if the clerk doesn't. :hatsoff: