That's a bummer about the tapered case, it may only be a few thousandths, but I would be worried at extraction issues at that point.
I haven't done any looking around for officer-length .38 mags, I was figuring I could cut some down to length if needed, since it might be unique.
Plus, I was under the impression that .38 Super = 9MM +P+. I know it's Wikipedia, but it looks like base Super loads get about 100 J more energy than 9MM +P, and .38 Super +P is comparable to .357 sig (which is about right, I have shot both). I just think .38 super auto is an awesome load.
Always carry an extra magazine when CCW. Friends don't let friends get a double-feed first round out.