In making mag bottoms, I've found it easier to use the radius cutter that cuts half the dia. at one time, as stability is a real issue with my limited equipment, and you can sneek up on your target overall width... But that being said, the MEC-GAR followers are probably some form of MIM molded part, where'as the originals were both sintered steel, and machined... Lot'sa ways to go... just need to get the cost per part under control... That would mean machining... Casting is pretty much too expensive, but it's really nice to avoid a gazillion machine operations...
.... BTW, The best follower outt'a all of them... is the late Mauser ones normally found in the code "122" and "fxo" mags.... cold drawn formed and then machined and heat treated!!!!...
.... til...lat'r....GT