Firing the 1911 without a recoil spring

A few years ago, I calculated the slide-to-frame impact based on a 5-inch pistol firing 230 grains at 830 fps. Without factoring in any resistance from the “recoil” spring, mainspring, hammer mass, or friction, it came to right around 9 foot-pounds. In normal operation, I’d estimate it at probably 7-7.5, assuming a 14-pound action spring…