I guess I'm lucky, as I have a pretty good supply of .45 AR brass for my Colt 1917. However, most of my use of the 1917 is with .45 ACP in full moon clips, as reloading is considerably faster. I do IDPA shooting with the 1917, so reloading speed is important. The only part I don't like is prying out the empties from the full moon clip - but I can do that anytime. My favorite removal tool is the corner of a steel ammo box.

A couple of years ago I lucked into three boxes of new .45 AR ammunition, Remington, circa maybe 1935 (the old dogbone style), for $10/box. I haven't fired any yet, and probably will not, as the boxes and cartridges are pristine.