-Quinch and temper-
As notorious as it sounds, on my "Vulcan" receiver nothing was hardened.
I bit the rails with a file before hardining.
So I took the easy way out instead of spending all the money on the fancy chemicals to quinch and temper by doing alittle research on metal properties. To demagnitise the metal or "rails" I used the ol' propane tourch to heat to around 1200 degrees or brite orange.
Then plunged into "Ice cold salt water", Yes (Salt) water. It does rust(surface) a tad but can be buffed out. And to use a good protectant. That is after you temper.
To temper: Heat the metal back to a dark blue, than let air cool.
The iodine in the salt combined with a quick quench is an instant "hard on"! Do a search and you'll find that "iodine" Is also a key ingredient in alot of the surface hardining compounds out there.
Many people say that a "Propane" tourch cannot heat 4130 steel to its hardining state like a "Map" or "Acedaline", to me that's B.S. You just need a little patients.
By "quinching" the part or peice this strengthens the internal carbon and the other properties of the metal.
By "Tempering" This is the surface hardining of the material. I would NOT suggest doing large parts in this procedure though. For the simple fact of warping the material. Use a kiln or furnace.
After Q&T on a peice of scrap stock, I burned up 3 Dremil bits just to get barely a 1/4" into the metal. If it's done right....It does work!
Making sure you get it right the first time, practice on a scrap peice.
If you continously keep heating and plunging, you could be breaking down the strength of the steel.....Making it very hard on the surface, but also very "Brittle"
After almost 2000 rounds.....No sign of ware on the ejecter!
Be carefull, the steam from the rapid quinch could be extremely harmfull!!!
Using oil to quinch is also a very good method to prevent rust and repell moisture. But can also cause a fire!! Again be carefull!
After all, you should clean your firearms by using a good moisture barrier regularly right? I'm guessing this would be a good method if you plan to store your rifle.......Or go swimming with it.