Now by now every one that is a collector knows about the wonderful steel cent that was made in WW2 to save copper.  Well here is how it really went. Like I said in the beginning the US government needed the copper for the war efforts so they went into testing phase. One of the test ones was a penny struck in tin but they scrapped that idea. Until they released their so they thought miracle cent, the 1943 steel penny. This penny had an inner zinc core with steel on the top of it. When they released it they had problems instantaneously. Since back in the day coins were a part of life vending machines had a magnet on the inside that would detect if a person was trying to put in a slug instead of a coin, the magnet would latch onto the steel pennies like magnets do and people would lose money. (a slug is a round object such as a washer that people would put into vending machines or other items to get a free item) another problem is that since they were made of steel they would rust very easily, and that was a huge problem because back in the day people would work get sweaty witch made their money wet and the penny rusted. So in 1944, they took back all the cents they could melted them down and instead used bullet cases as the coin alloy.