Type 2A/B The main milled receiver created from metal forging. It went into manufacturing in 1951 and manufacturing ended in 1957. The sort 2A has a distinctive socketed steel "boot" connecting the butt stock on the receiver and the milled lightening Slash on the edges runs parallel towards the barrel. https://guns01110.blogoscience.com/21576273/how-much-you-need-to-expect-you-ll-pay-for-a-good-sig-saeur-handguns