Al likely cut those moulds to be on spec for weight using WW alloy. Nothing wrong with range scrap, but that is likely where your weight difference and nose marking issue are coming from. Your particular batch of scrap "may" be mostly pure or nearly pure due to lots of 22 and similar slugs in the mix. Just for argument sake try casting a few with WW alloy and see if the nose marking goes away, as you may possibly be compressing the nose enough to leave that marking. I also have a "BUNCH" of NOE moulds and find them to be very close to as advertised for weight and dimension!