Oven heating

[jonk]

I'm rather sure this has been covered but 3 search queries turned up nothing to match my question.

When you oven heat a cast bullet to increase hardness, at what temperature and for how long? Air cool after?

[docone31]

Never oven tempered. I water quench. That, so far, is all I need to do.

[Ole]

I use an old toaster oven to treat my .44 bullets. Make sure you have a separate oven thermometer, as the thermometers in those toaster ovens aren't very accurate.

As an example: I set my T.O. @ around 390 degrees, and it comes on around 438-440, shuts off just over 450.

That's where I set it though. Dump the bullets in a big bucket of water after they spend an hour in the oven.

[MtGun44]

As hot as you can get them without slumping, then water quench. You need about
an hour at temp before quenching. Hardness is not immediate, but builds up over a
period of days to weeks. Will not work with pure lead and tin, need antimony and better
if some arsenic, too. Many folks use 450F and get good results. Test the oven with a
few rather than slumping a whole bunch of boolits.

Bill

[Maven]

jonk, You need to heat treat your CB's for ~50mins. for at least 45mins. @ 450 deg. - 465 deg. (It's better to size them first.) Here's how Dennis Marshall, Jr. describes it*: Bring the oven up to 470 deg. and stand 2 or 3 scrap CB's from your batch on a tray for ~20mins. If they begin to slump or show signs of melting, reduce the oven temp. by 5 deg. Repeat with 2 or 3 more scrap CB's and continue to do so until you've reached a temperature that won't melt your CB's. (Don't ask how I know this!) Make a note of that temp. and the oven setting for that alloy so you can re-establish it at another time. Make a basket of hardware cloth (a metal grid with ~ 1/4" squares) and a bale or handle for it. Stack your CB's in it no more than 2 layers deep. Put it in your preheated oven for 50 mins. to 1 hour and then remove and immediately quench (Don't dawdle!) the CB's in cold water. Marshall's process will bring WW alloy to 18 -21 BHN immediately and as high as 30 BHN after several weeks.


*You can find this in the NRA "Cast Bullets" book as well as The RCBS volume (II) with the same title.

[AZ-Stew]

Jonk,

Read this thread: http://castboolits.gunloads.com/showthread.php?t=42870&highlight=toaster

It is a report on my use of a yard-sale toaster oven for heat treating. It has insights about testing methods, info about the thermostat in these devices and the (impressive, to me) final results.

Regards,

Stew

[243winxb]

http://castboolits.gunloads.com/showthread.php?t=52686 Lyman - Heat Treatment of Cast Bullets to Harden Them

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Quote:
Q: Is there anything I can do to make the bullets harder?
A: Cast bullets can be heat treated to increase their hardness providing your alloy has some antimony present. To heat treat your bullets: Cast your bullets in the normal manner, saving several scrap bullets. Size your bullets but do not lubricate them. Place several scrap bullets on a pan in your oven at 450 degrees and increase the temperature until the bullets start to melt or slump. Be sure to use an accurate oven thermometer and a pan that will not be used again for food. Once the bullets start to melt or slump, back off the temperature about 5 to 10 degrees and slide in your first batch of good bullets. Leave these in the oven for a half hour. Remove the bullets from the oven and plunge them into cool water. Allow them to cool thoroughly. When you are ready to lubricate, install a sizing die .001" larger than the one used to initially size them. This will prevent the sides of the bullets from work-softening from contact with the sizing die. Next apply gas checks if required and lubricate. These are now ready for loading.

Many more casting tips at Lyman, look here>> http://www.lymanproducts.com/lyman/f...et-casting.php Not sure how the process works, but if the treatment brings the antimony to the surface of the bullet, i would think you would get leading.