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 and 23-pound mainspring.
Here is a video of a demonstration I have performed many times with this 1911. I put it together using a cast slide, frame, and parts I had lying around. After each demo, I field-strip the pistol and look for any damage.
This serves to lay waste to the myth that the slide will beat up the frame unless heavy springs and/or shock buffs are used…or that light springs will cause early unlock timing.
The plain truth is that the slide just doesn’t hit the frame all that hard.
And the timing isn’t at all affected by the spring.