I have a couple that were made of polymer on the civilian market a few years ago. Works just fine, the only thing is they are a bit thicker than the originals so you have to line them up perfectly with the action to fit the charger in.

Can't help you with drying out. If they aren't falling apart I personally wouldn't worry about it. These are 60+ year old items at this point, I am amazed at how well they have held up all things considered.