If you look carefully at the dimensions, there's maybe a quarter-inch of clearance between the back of the slide where the spring plunger fits and the front of the factory spring guide.... there's no way the spring can "kink" in that dimension, so the "guide rod" is basically a way to suck money out of your wallet and make the pistol a bitch to field strip w/o tools.... never was a part of JMB"s design for a good reason