[DonVoigt]

The drawing gives pin dimensions aof 2.5mm diameter and 13mm long.
The pin actually holds the lever in its recess, and the spring tension of the arm in the detents also acts to position the lever; the pin does affect the rotation if too larger in diameter or too long.

I would try a little polishing of the diameter and see if it improves.

Like I said before if the pin is a little too long it gets very hard to move the safety.

You don't mention if the safety is matching or not; they are not "universal" and are fit to the frame- though usually pretty close to interchangeable.