I have the Wheeler Engineerng 72 pc set and am more than happy with the different selection of widths and thicknesses.
From what I have read about the European guns is that the screws are thinner in the slot area than most of the American guns.
I have recently acquired a Greener circa 1892 and wanted to look inside to inspect everything. Found the bits that fit the narrow slots and could not break some of the larger bottom reciever screws loose. So left them alone.
I don't know what they used to do the job, but ater this many years it is possible that moisture worked it's way to the threads. Might need some pentetrating oil and try again.
