I was having trouble with feeding in my Springfield XD 45 ACP Tactical and needed new springs. I thought I would try the AGP springs because the factory springs only lasted a year before I started to have problems. AGP initially sent me the wrong springs for the 13 round magazines which did not fit the 10 round magazines. I called AGP and they quickly sent out the correct springs which I had two days later. The 10 round springs fit great an appeared a lot stronger on the first loading of the magazines. The second loading of the magazine the tension decreased enough I did not have any problems loading the magazines. Comparing the springs to the factory springs I found they both have the same number of coil's and have the same diameter of wire. Not sure they are 20% stronger than the factory springs because they are the same size as the factory springs. One thing is a fact the AGP springs work good and all my failures to feed stopped.