FN's internal firing pin safeties were introduced with
late runs of the Mk II circa 1987-1988. (Initially runs of the Mk II did not have it nor did the "classic" style of Hi Power.) Some of the Mk III pistols didn't have them but the majority, actually desginated Mk IIIs, did. This would be around 1989.
One can tell for sure if his/her Hi Power has the internal firing pin safety by removing the slide and looking to see if a hole has been milled in bottom of it for the "paddle" on the rear of the spring-loaded sear lever to extend through and block the firing pin's forward movement until the trigger's pressed.
This is what the bottom of the slide looks like if it does have the internal firing pin safety. If it doesn't have the milled opening at the rear with the end of the sear lever being a "paddle", it does not have an internal firing pin safety.Best.
