Grey silver finish only on deeply engraved Simson's made in GDR. Known as model 76 with sideplates and mod.74 without sideplates.
All actions that look like yours got case colors. Maybe there were grey finish plain engraved Simson, but personally I didn't see one.
BTW, you could check it yourself. If c.c. were deleted by previous owner or dealer there are must be c.c. traces inside the receiver. Take action and stock apart and look inside.

Geno.