Try it. So long as they stay dry, I don't see why not. But as much as I like ziplocks, I don't always trust them.

The danger is when you go for a swim or get caught in the rain. Rain gets in with the bullion cubes, you get bullion. If the rain gets in, the bag has failed. Failed bag let rain in, will let bullion out. Assuming that the outter bag mostly works, then you get survival kit stew with a base of bullion. Everything smells and tastes like bullion.

Bears like bullion. So do skunks, racoons, porcupines, and perversely enough, chipmunks and squirrels. Probably catamounts and bobcats, to. No one you want interested in your survival kit. And it would be worse if you wore some of the stew.

The only think I'm more protective in terms of water getting in is matches and my FAK.