I was looking at the CZ web site and they have lots of small parts cheap. Little stuff like pins and springs for around 2.00 bucks. They probably just changed something simple like the wire diameter to change the spring rate to increase the firing pin impact force. Also McMaster Carr and Lee springs would be a good place to get springs. Avoid stainless steel as they actually have a spring rate of approximately 85% of the music wire type. Meaning they are weaker given the same size. I just looked at taking my 457 bolt apart.... what a PITA!I have been reading about the ignition on the 455's being improved with a new spring, anyone know if the spring is the same from the 455 to the 457? I'm mainly just playing around to see what I can get out of the little gun so I figured a cheap spring would be worth trying.