Hello Ian,out of 8 wartime magneto's I have 2 are brass, 6 are steel.If thats the way they left the works I have no way of knowing.Its only when the factory finish wears off that you can tell.Regards Sam.
I bought an old M01 off ebay recently, and it has a brass points cover with what looks like nickel plating.
I have been trying to remove the nickel as it has deteriorated in places.
It is the same dimensions and shape as the pressed steel type
Can't check the Mag year from the ID tag at the moment unfortunately.
Only one I have ever seen.
Cheers Keith