If the springs are of the Chrome Silicon variety, they will supposedly do up to a million cycles. They were developed for Nascar engine valves (if what I read a few years back is true) and found their way into mil-spec gun actions, high mile diesel engines and a host of other mechanical devices. For an actual definitive answer, I would write Progressive's engineering department for a metallurgical makeup and expected spring cycle life. In the old days, springs were made of O-1 or Improved Plow Steel, but as one could expect, we have come a long, long way from there.
