Question About Heat Treating

[jonp]

I just bought a toaster oven to try heat treating some boolits as I'm getting leading in my 32 H&R Mag. I've tried different lubes, sizes and cast hardness now I'm onto heat treating to see if I can track it down.

My question is about heat treating and I can't seem to run down the answer here on several threads. Is there any difference in heat treating boolits that are several months old vs newly cast if both start out at the same BHN? IE: does age have any bearing on the final hardness?

[sureYnot]

The newly cast would harden over the next couple weeks. The older stuff has already done that. So, if they're the same hardness now, the newly cast must have more antimony and/or arsenic. Theoretically, if you heat treat both the same, your newly cast would end up harder than the aged stuff.

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[Yodogsandman]

Boolits cast several months ago and those cast recently will oven heat treat the same if they are made of the same alloy and all other parameters are the same. Either will still need to be age hardened from a few days to a week to reach full hardness potential after oven heat treating. The time to age harden will depend on the alloy and temperatures of the oven and water for quenching. Also how quickly you can fully cool those hot bullets dictates hardness, too.

Just age hardening cast bullets takes about a month to reach near potential depending on alloy.

Alloys rich in antimony will harden more. A little trace amount of arsenic will speed up the process a little. Tin is detrimental to heat treating, it takes longer to reach it's potential and loses hardness quickly (it starts softening under a year old).

I'm curious why you're jumping right to oven heat treating your boolits as opposed to water dropping right from the mold into a bucket of quench water. Water dropping will bring COWW alloy to about 15-18 BHN. Oven heat treating will bring COWW to about 22 BHN. Oven heat treating is more consistent if boolits are allowed to heat soak for at least an hour before quenching.

Rick Kelter has an excellent article on oven heat treating over on the LASC site.
http://www.lasc.us/Kelter_Heat_Treat.pdf

[jonp]

Thanks for the info yodogs. Just what i was looking for.

Why? For the same reason powder coating is on the list of things to do. I've never done it and want to see for myself what varying temp and times in the oven will do to different alloys and what velocity/bhn does to expantion. I could read all of this and have through this sight but this is a hobby afterall and I like to see things for myself.

I have water dropped. Seems like I can get a greater control of BHN for experimenting using an oven than water. I did find it interesting that cold water vs room temp seems to make no difference.

[sureYnot]

Here's some good stuff about it to help you get started playing with it.

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

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[jonp]

Here's some good stuff about it to help you get started playing with it.

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

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Dang, I've been on that sight a bunch looking at BHN, alloy mixes etc but for some reason forgot that I'd read that a few years ago. Thanks for the reminder and especially for the chart at the bottom on heat times

[sureYnot]

Yeah. It's pretty neat how much control you can exercise on it.

Can't remember who, but there was a guy posted in another thread in the past few weeks that he did a hardness test on some bullets he's treated over ten years ago. They were marked as bhn in the low twenties, I think, and had only lost two points in that time. So, it isn't like you have to get em shot up in a hurry, either.

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