Tricky, I turn and mill 4130 & 4350 , in their hardened state, every day. Roughing cuts on the lathe .06 deep @ .008-.01 I.P.R. Most all milling is done on CNC mills, machines so much larger than Bridgeports the only compairison is they both use end mill type cutters, some inserted some not. C6 brazed carbide easily cuts through Melonited surfaces , like a barrel crowns. Good inserts, even better. My question is why would an action need to be harder? Most items that take a "shock" are designed to have a certain amount of "spring back" to them, so they return to their original shape (like an axle does). I think if I read H&Ms' policys correctly you'll find that they claim no responsibility for the suitability or application of the part(s) being treated. In the past Meoniting was mainly used on bearing surfaces (the rifled bore of a barrel is a "bearing surface"as are crank shafts and cam shafts in large, industrial applications). 4140/416R can be ordered from the mill in any hardness obtainable, as long as the order is large enough. By what I read on the boards, few understand that modern bolt actions are made of pre-hardened stock (so are barrels), not hardened after they are machined. The uneven sections would allow too much deflection if hardened after machining. I'm not against advances in technology, I'm just questioning "does an action need to be any harder than it already is?".
