[lugerholsterrepair]

Ron is right on the money..These sights can be tricky. They are are also delicate. The first time I ever tried to turn one it broke the sight adjusting tool..There went $65 out the window back in 1990.

Other than the novelty of moving these there is usually no reason to do it.. particularly on a pure collector pistol.

I'm sure replacement screws are darn near non-existent, but I bought this thing to do some long distance pistol-shootin, so I do need it zeroed

Well in that case I would soak the sight as Ron says for some time. I might have a replacement screw around here I bought years ago..I think the front and rear are different?

I also had a special run of French fitted sight tools made with concave heads and steel tempered tips specially for Artillery sight adjustment screws. You might want to think of goint to the hardware store..they actually make a spanner screwdriver tip that might be small enough.