Actually winding and setting a new spring from piano wire is not that tricky.. you can do it on a (metal) lathe with a winding tool made of a lump of wood with two nails in it. once you have wound it stick it in a metal pan with kero and sump oil and burn it off...! Making the end cap however is going to be fun - internal thread of unknown form!

That said, I rarely use the mag on my Lebel.. even using the new PPU ring base cases the thought of all those points next to the primers kinda puts me off a bit!