Hello! I bought a great 19 at a gun show last weekend! It is a 4-screw with s/n K381XXX. It is not marked mod 19. Do you all think this is a pre-19? The s/n date puts it at 1959 (I checked the book), but of course they started stamping model numbers in 1957. So is it a pre-19 or a Mod-19...