heat treating

[castmiester]

I just read in Lymans 3rd edition about heat treating. So I ran my oven at 440 degrees for 15 minutes with a cast out of WW's. It went form 10 to 15 BH in 15 minutes. They said it can reach 30 if left in long enough. For expansion for hunting, is performance with heat treatment the same as adding alloy?

[Bigslug]

STRONGLY suggest you look up at the "stickied" threads up at the top of this Cast Boolits subforum and click on the one titled "From Ingot to Target: A Cast Bullet Guide For Handgunners"

This will tie you into Glenn Fryxell's excellent book that'll get you past the steeper parts of the learning curve.

[waco]

http://www.lasc.us/HeatTreat.htm

[JonB_in_Glencoe]

you need at least 30 minutes, best to do 1 hour, to fully sink heat into boolits for heat treat.
The Temp of the boolits the second they hit the water and the water temp are the factors that will predict the hardness. Maintain those two factors and you will get reliable hardness batch to batch.

[castmiester]

saw the chart for oven heat treating. It specifies 1 hour, thanks. I read in Lymans #3 a half an hour, is fine though. Didn't factor in age though. Lymans writer didn't mention raising temp in oven, but did mention about watching for drooping and melting at 450, then to lower 5 to 10 degrees. The cast didn't melt at 450 but I dropped it to 440.

[20:1]

saw the chart for oven heat treating. It specifies 1 hour, thanks. I read in Lymans #3 a half an hour, is fine though. Didn't factor in age though. Lymans writer didn't mention raising temp in oven, but did mention about watching for drooping and melting at 450, then to lower 5 to 10 degrees. The cast didn't melt at 450 but I dropped it to 440.

That's the exact makeup of your particular alloy at play. If you're using scrap for your alloy your results are likely to be different the next time.

[fredj338]

15min certainly gets you a bump equiv to adding lino or such, but the exact bump is very alloy dependent.

[castmiester]

That's the exact makeup of your particular alloy at play. If you're using scrap for your alloy your results are likely to be different the next time.

Nothing noted about it being scrap or not. I am aware of different alloy content of various years of manufacture. Initially they tested at 9 before the tin.


All bullets heat treated and tested were with clip-on wheel weights + 3% virgin bar tin.
But did note this....

Thermometers, oven controls and especially BHN testers all vary, you may need to do a little tweaking of the numbers to achieve your desired BHN. The amount of antimony and tin in your alloy will affect the time to age harden to the final BHN and the time and amount of age softening.
Additional testing is planned with various alloy recipes such as clip-on wheel weight at 3/1 with straight lead and the effect on the hardening/time curve.

that is from the article and the chart notes below it. Nothing noted about it being scrap or not. I added some tin, and actually the BHN was 10 to start before heat treating it.

[Calamity Jake]

I've always used 425 oven temp and 1 hour heat time then ice water quench as quick as possible from oven.
This process takes my 75 %WW 25% lino up to 22 BHN

[waksupi]

You can vary hardness according to what temperature you set your oven.

[longbow]

For expansion for hunting, is performance with heat treatment the same as adding alloy?

For expanding boolits for hunting you would not want to heat treat to make harder boolits, you want a malleable alloy that will deform without breaking up.

There are posts on this site with good info on hunting alloys:

https://castboolits.gunloads.com/showthread.php?422707-expansion-and-FPS-to-hardness-thoughts

Larry Gibson has a good post there.

Some more discussion on alloys:

https://castboolits.gunloads.com/showthread.php?357479-Hunting-alloy-questions
https://castboolits.gunloads.com/showthread.php?232347-Preferred-rifle-bullet-alloy-hardness-for-medium-game

Longbow

[popper]

Alloy needs to be 2% Sb for much hardening to occur. Add some (1/2% Cu) and hardness goes way up. I've gotten to 36, pure Cu is ~40. It makes a very tough bullet.