This drill is .076" and the original port size is .077".
More than likely with a cheap drill press or hand drill the bit will cut
oversize so it won't really matter. The original hole looks to be
drilled with a .156 or 4mm spot drill then drilled with the smaller
All the drills that I buy are the screw machine style which is
shorter and will flex less than normal jobber drills that you buy from
the hardware store.
The picture doesn't show the drill, but only the drill will be sent
not the gas block obviously. The picture shows how the hole should look