Ask the Community

The 70 series lack a firing pin block, According to Colt : Series 80 : Colt released a new 1911 design dubbed the Series 80 (also named for the decade during which it was released) with a few design changes. First was the addition of a trigger-actuated firing pin block. Similar to the transfer bar safety common to double-action revolvers, the trigger must be pulled to unblock the firing pin.

Its mostly to indicate its newer. The differences are extremely minimal.