I've only taken the buttplate off 4 Shelhamer rifles from the Niedner days, but none of those had his stamp. Every later rifle I had had a chance to take apart has had the stamp and number. It is a one piece stamp. For what it is worth, I have seen at least one rifle that said T Shelhamer under the buttplate stamped with individual characters. The workmanship on said rifle did not support it being made by the same Tom Shelhamer that we are familiar with.

John