Maybe as light as 14 pounds, but if it will cycle with a 16 pound spring, then anything lighter will lead to battering. I use a light load of 3.6 grains of bullseye with a 185 grain bullet in my Kimber and it works fine with a 14 pound spring.
Another option is called, I think, a slide racker. There are various designs. If you go to brownells.com and search for racker 1911 you will see one option. There are others. You could rest the racker on a wooden shooting bench, then rack the slide by pushing the gun down.