Just as an aside, these are very interesting posts on another forum regarding 1911 magazines and their design, evolution and how they intergrate into the overall reliability of the 1911 platform. Fairly quick reading.
http://230grain.com/showthread.php?4...s-(part-1-of-3)
http://230grain.com/showthread.php?5...nalysis-Part-2
(part 3 is down the page title "ammo".)