A nail may be a start, but once the opening is punctured, using any remaining 4200 more than a few weeks later will become more and more of a problem.
4200 caulk is set off by contact with moisture - humidity in the air. Once any air gets into the cartridge, the whole thing starts to harden. Sticking a nail into the opening might enable MORE air and moisture into the cartridge than was already there. You might be better off with a cap over the top, and trying to allow the caulk in the tip to become (because it's been exposed to the air) a plug. Maybe sticking the tip into a glob of silicone sealant? Before I open one of those things I try to make a LONG list of places where it could be put to use, and try to use all of it, or as much of it as possible, at once. 5200 is even worse. Don't forget to wear gloves!