A little misunderstanding here. The "nub" that operates the magazine safety is not just a pin, it is a plunger with a small spring behind it. In other words, the mag safety is not operated by the recoil spring, it is operated by its own spring. The spring and plunger are a permanent assembly in the later type recoil spring guide and normally are not available separately. I think a good gunsmith should be able to fit new ones, but the cost would be higher than just buying the right recoil spring guide.