Well I searched for hours yesterday, but to my surprise, I could not find ANY 0.75" OD tube with less than 0.5" ID!
This is for a hot-melt (250°F) glue nozzle. I wanted Al for its thermal conductive properties. I even considered brass, but I could only find sources the right size in India and China.
I finally ordered a DOM tube from onlinemetals.com this morning. I can live with a slower warm-up time, it is just not ideal.
Thanks for the help though!