The very first Trophy Hunters with synthetic stocks had the plastic bottom metal/surround. However, given how Savage never stops looking for ways to save a few pennies and increase their profit margins, they realized they could mold that surround right into the stock the same as they do on the Axis stocks and save the money and hassle of having a separate piece for those models. Thus the molded-in stocks like foxx's were born and are now the standard.