I have a 50cent piece that is missing the back side of the coin. 1971D. Is this a real coin that was altered after is was minted?
Most likely. In order for the Obverse (front) side to be struck correctly you need equal pressure on both sides of the blank planchet. Do you have a picture?
OK. What you have is a normal 50 Cent piece that was machined. They hollowed it out to make a magicians coin.