Is This True

[Gohon]

Reading a article by Rick Kelter at http://www.lasc.us/HeatTreat.htm my attention was caught by his comments of controlling BHN with heat treating. In particular near the bottom there is a chart of different oven temperatures and times to attain different BHN hardness. For example when starting with a BHN of 10, with the oven at 420 degrees and the bullets heated for one hour then quenched in water at 58 degrees the BHN after 96 hours will be at 18 BHN according to tests and stabilize in 7-14 days. The same load at 400 degrees for one hour would result in a hardness of 15 BHN or at 460 degrees for one hour would give a 25 BHN hardness. I guess my question is has anyone confirmed this or know if it to be true. Seems just to easy.

[snowwolfe]

I can't confirm if his information is true but the Lyman Casting Softcover book dated 1980 mentions how to increase the hardness of the bullets by using the oven method as well.

[MtGun44]

Haven't looked up the particular temps, but if you are using
an alloy with antimony (like wheel wts) you will get different
hardness from quenching from different temps. This is well
established, and the time for the hardness to set in is also
not instantaneous - it takes days. SO - basically - the info
is well known, in the references on bullet casting, but I can't
verify that the number quoted are correct. Sounds like the
straight dope without doing the research to verify.

Bill

[454PB]

Yes, the basic principle is true, and Rick knows his stuff about heat treating, so I would accept it as accurate. He is also a member of this forum.

[andrew375]

The process is called "precipitation hardening".

[DonH]

Not only will varying the temperature change hardness but varying the time of the "soak" wil as well. I haven't done this for years but I have attained a hardness of 35 bhn before from heat treating bullets cast from WW. If I state the temp settings and time my memory may not be correct but I do recall that a longer time at higher temp resulted in 35 bhn and through experimentation, about half the time at a somewhat lower setting yielded 25 bhn. All were quenched in a 5 gallon bucket of room temp water. HT WW 429421 bullets at 25 bhn were loaded in .44 mag cases over 25 grains of W296 powder with no leading and with good accuracy so I saw no need for the higher bhn levels.