I’ve wondered if Springfields need to be re-heat treated after truing or rebarreling. I know some of the early ones were poorly heat treated, and you’re not supposed to use them. And apparently you can’t re-heat treat them. But on the other hand they say that the “double heat treated” actions and the nickel steel actions are fine. Is this because they think they created too much austenite in the failed heat treatment or what?

And Nickel Steel’s an alloy steel, right? So I think that should’ve been through-hardened rather than case-hardened. There must be something I’ve gotten wrong here, but I’d like to understand it.

Thanks,
Steve

Whoops, sorry. Found the answer in Hatcher's Notebook on Google books.

Short story, for future searches:

1) Early receivers were medium carbon (through-hardenable) steel. They were case-hardened (and through-hardened). Many were overheated to the point that the metal has changed to brittle crystalline structure that can't be fixed by re-heat treating.
2) Double heat treated actions were case hardened at 1500. Then they were re-heated to 1300 so that interior was drawn/softened, but exterior with the high carbon from casing was rehardened. Then drawn again at 370 (check this, but I think 370 deg).
3) Nickel steel was just hardened and annealed at higher temp (6XX degrees).

Hatcher's tests show double heat treat actions outperforming the nickel steel actions in proof testing. They used 70K to 125K psi loads, and in some cases tested to failure. The double heat treat's grew headspace but didn't fail.

Steve

The nickle steel Springfields are known as being sticky; double heat treated actions were smooth as silk to operate.