Not hot enough .. crucible needs to be cherry red. That is why the colors are mostly tan with not much blue. And you won't get a hard case unless you get the parts above critical temp circa 1350F before quenching. You may get some color but no hard case. And that's the main point .. hard case prevents wear and to some extent, corrosion. You may want to get finer charcoal flakes as well, keeps the air off the parts.

Thanks for your wonderful videos of "building double rifle". I can't find the number one of theese. Could you help me ? Matteo

Would like to know the cost of one of those double rifles in 458