Oven heat treating

[tommyn]

I did a search and didn't find what I was wanting. I have 200 45 cal cast bullets I want to try heating to harden. Please help. Would you size before heating and what temp and how long in oven. Do you drop the heated bullets in water after. Help.

[James C. Snodgrass]

Now don't hold my feet to the fire if I'm off a bit on the #'s, and I think its on the LASC web site. I did mine at 475-450 for one hour then water drop. I do know that you have antimony in the mix to gain anything from heat treating . The only thing that doing it with a oven provides is consistency as opposed to dropping from the mold into water. I hope this helps you know my memory ain't as long as my hair, And it's so short I ain't seen it in years. [smilie=1:

[Shuz]

I did a search and didn't find what I was wanting. I have 200 45 cal cast bullets I want to try heating to harden. Please help. Would you size before heating and what temp and how long in oven. Do you drop the heated bullets in water after. Help.

Yep, size the boolits before you heat treat them, otherwise the sizing operation will "work soften" the outside of the boolit. Heat them to 450F to 475F for about 1/2 hour and then drop them quickly into water. Room temp on the water has always worked for me. Wheel weights done this way will often hit 22 Bhn.

[ktw]

I have been sizing and gas checking prior to heat treating.

I stand them up on an old aluminium camp plate. I cut some rings out of tin cans to stand them up in to keep them standing while moving the plate around

I put them in the oven for 1 hour at 450 degrees, then quickly drop the whole plate full into a bucket of cold water.

This takes my normal wheel weight alloy (~13bhn) up to around 24bhn after a couple of days of curing. These are primarily 270 and 30 caliber rifle bullets.

I then run them back through a lubesizer with the same sized sizer die for lubing.

-ktw

[blackthorn]

If you decide to oven heat treat, a thermometer is not required if the oven temperature dial is known to be within specifications, but the use of a thermometer greatly enhances the process of learning the idiosyncrasies of the oven that is to be used. Start with the oven set at 475°F on the dial, stand some reject bullets on end, on a pan, and leave for one hour. If they slump or change shape, drop the temperature 25°F and replace the test bullets for another test run. Continue down to 425°F if necessary. Your oven dial may be a little off, and your thermometer will show by how much. Record the oven temperature where the bullets remain perfect after a one-hour soak for future reference. Remember however that future batches may be made up of slightly different alloy and that simple fact alone may result in a plus or minus change in the oven temperature needed. The time at the ultimate temperature (along with a quick quench) is critical; so do not raise the heat in an attempt to shorten the time. Always use a one-hour (or more) soak from a cold oven, perhaps 55 minutes for a preheated oven. It takes time for the constituent molecules to equalize throughout the bullets. You don’t want to make them ‘nervous’ with intense heat. Constituent uniformity coupled with a quick quench is the key to successful heat-treating. Keep the bullets as close to the centre of the oven as possible, because if the bullets are more to one side than the other the heat will not be evenly distributed. Put a piece of aluminium foil, about 12”x18”, in the centre of your oven for better heat distribution.

It is certainly acceptable to use a preheated oven but remember that when heat-treating in an oven it actually requires a one-hour soak to bring the bullets up to the optimum temperature. One of the biggest variables you will face when heat-treating is the oven itself, i.e. some are much more consistent than others. Remember to begin by setting the oven at 450°F, let it stabilize, and put one or two reject cast bullets (CBs) on a tray in it for 20 minutes. If they do not begin to melt/slump after that time, raise the dial to 460°F and watch them for another 20 minutes. Continue raising the temperature until they begin to slump/melt, then back off 5°F to 10°F. This will establish the maximum temperature that will result in the highest level of hardness for your CBs.

During the actual heat-treating process you can lay the CBs on their sides and layer them two-deep if you make a basket of wire mesh (1/4” grid) ‘hardware cloth’. Heat-treat your batch of bullets at this temperature in the oven for one hour and they will be ready to be quenched. The time it takes to get them from the oven to the water is critical! A smooth, speedy transient response of the heated lead to the cold water is the mechanism that makes the bullet go hard. Have the bucket of ice water right beside the oven and lose as little time as possible in transferring the bullets from the oven to the water once the oven door is opened. The need for a full hour in the oven is required because all the constituent activity within the bullet must be as constant and quiet as possible when quenching occurs in order to maximize the transient effects. If you dump the heat softened CBs into the water you can damage them. Remove them from the water and towel dry them as soon as possible or they may begin to corrode (depending on the mineral content of your water). Once dry, you can either tumble lube them or use a lubrisizer die that will not do any actual sizing of the bullet because you do not want to risk disturbing the constituent composition of the now hard bullets by pushing them, with force, through your machine. Besides being difficult, sizing after heat-treatment work softens the sized portion of the CB, which defeats your efforts. Label the storage container with a date and allow the bullets to age-harden for another three or four weeks before use.

[Firebird]

Don't forget when sizing before heat-treatment that since you aren't putting any lube onto the bullet that the bullets need to have some lubricant put on them prior to sizing. Just a shot of one of the case sizing spray lubes will work, or just rub a little bullet lube on the driving bands every couple of bullets. The lubricated bullets will be much easier to size than if you tried doing them dry.

[targetshootr]

Did you cast the 45s or are they 'store bought'? Commercial boolits are fairly hard already. And if they're for use in a handgun you may not need to harden them at all.