Where do I get a custom gun part fabricated?

Any machine shop or competent Gunsmith can do it.* The old ammo you are using is A-OK, and it isn't what broke the spring.* Age and wear and tear on the spring finally gave out, or a weakness or flaw in it is what caused it to break.* Don't blame the old ammo.* No the older ammo doesn't become more potent or powerful.*