Simply amazing, and what an eye for detail!!
Thats also why I will come with just a tiny bit of nitpicking.
As far as I know, The screw you used for the grip, is not the safety. This screw, locks and unlocks the grip, and on a real sterling, your grip would fall off right now, as its in the free position.
The real safety is a part of your selector switch.
The selector groups on the sterling shows, from left to right: A=automatic. R=Repetition. S=safe.
But I must agree with skunky. This is by far the most acurate scratch built sterling, I have EVER seen!!!
EDIT: And should you ever make this as a kit, I'd definetly buy one