Looking over this thread I thought I'd point out a few changes made over the years. In 1948 there were two, the words "TRADE MARK" were replaced with a circled "R", and the words "Sweet Sixteen" were engraved on the receiver. But evidently not at the same time, as my '48 has the first but not the second change. In 1951 the front safety went away in favor of the cross bolt. I'm indifferent to which style is used except on Sweet Sixteens (and early Light Twelves) as I really like the look of the gold safety paired with a golden trigger.