Help Me With Heat Treating -- Please?

[captain-03]

I have been reading a few post regarding heat treating cast bullets ... seems like it is something I would like to try in order to push some rifle bullets a little faster .. Got several questions about the process ....

1) What is the best method to actually perform the heat treatment .. temps, lenght of time in over, temp of water they are placed in, etc, etc ...

2) What can I expect to gain in harness from heat treatment using straight wheel weights or 50/50 WW to Pb?

3) I have read that once you heat treat and then resize, the bullet looses some of its gained hardness - true? Do you size then heat treat?

4) How about gascheck bullets, do you go ahead and check them prior to heat treatment?

5) When do you lube? Soon after treatment, or do you wait until you get ready to load 'em? (I use an RBCS lube/sizer)

6) How long can I store the treated bullets before they begin to soften?

7) Any advantage in heat treating pistol bullets (9mm, 40S&W, 45ACP)?

I know that I have asked a lot of questions, but I know that there are some of you who have ALL the answers!! Thanks!!

[grumpy one]

I have been reading a few post regarding heat treating cast bullets ... seems like it is something I would like to try in order to push some rifle bullets a little faster .. Got several questions about the process ....

1) What is the best method to actually perform the heat treatment .. temps, lenght of time in over, temp of water they are placed in, etc, etc ...

Probably like most people, I use the oven temperature as the way I control how hard I make the bullets. Always leave the bullets in a preheated oven for one hour before quenching. If you want to raise the hardness of straight WW, which is about 10.5 BHN air cooled, to 16.5 BHN, an oven temperature of 185* Celsius should do it (hardness always measured 14 days after HT). That is using tapwater at room temperature, but you need to get the basket of bullets from the oven into the water within say 1 second.

2) What can I expect to gain in harness from heat treatment using straight wheel weights or 50/50 WW to Pb?

WW don't have a standard composition. If you have say about 0.7% Sn and 2.5% Sb (i.e. a mixture of clip-on and stick-on WWs), and you do a maximum quench (i.e. oven temperature 240* Celsius - any more and the bullets slump in the oven) you'll probably get 24.5 BHN. If you use about 1.5% Sn, 4% Sb you'll probably get about 32.5 BHN. The hardness achieved falls off fairly slowly on the lower-Sb side: 2% Sb should give you about 23.5 BHN. I haven't tried lower Sb content than that.

3) I have read that once you heat treat and then resize, the bullet looses some of its gained hardness - true? Do you size then heat treat?

Yes, after the bullet has hardened (i.e. hours to days after quenching) if you cause the metal to yield, most of the hardening will be lost. Most people size before heat treating, but those who water drop direct from the mould size within say 2 hours of casting, and still get quite a bit of hardening.

4) How about gascheck bullets, do you go ahead and check them prior to heat treatment?

You could, in fact it's recommended, but it gets pretty annoying if you change your mind about the alloy or HT afterward since you'd be wasting expensive GCs. There are a few tricks sometimes done to delay GCing the bullets, such as sizing without GCing, then GCing later when lubing, in a sizing die .001" oversize. I'm not really sure whether this gives the same accuracy as GCing before sizing.

5) When do you lube? Soon after treatment, or do you wait until you get ready to load 'em? (I use an RBCS lube/sizer)

Depends on your lube and storage process. I don't like the idea of letting the lube dry out before shooting the bullets, so I'd rather leave the lubing (using a .001" oversize sizing die) and cartridge loading until just before shooting them.

6) How long can I store the treated bullets before they begin to soften?

The hardness increases and decreases simultaneously due to different metallurgical processes. Peak hardness is likely to occur a few weeks after HT, but the bullets will still be a lot harder than air cooled after a year.

7) Any advantage in heat treating pistol bullets (9mm, 40S&W, 45ACP)?

I'd better leave that one for people who shoot those calibers. It may depend on the particular pistol. Hardening isn't necessary for any of those, but whether some barrels turn out to like hard bullets is another question.

I know that I have asked a lot of questions, but I know that there are some of you who have ALL the answers!! Thanks!!

I don't know if anyone has all of them, but between all the members you should be able to get most of them.

[Bret4207]

I have been reading a few post regarding heat treating cast bullets ... seems like it is something I would like to try in order to push some rifle bullets a little faster .. Got several questions about the process ....

1) What is the best method to actually perform the heat treatment .. temps, lenght of time in over, temp of water they are placed in, etc, etc ... I prefer to water quench out of the mould into a 5 gallon sheet rock bucket full of room temp water. Water temp has made no discernible difference to me this far

2) What can I expect to gain in harness from heat treatment using straight wheel weights or 50/50 WW to Pb?5-8 points Bhn, maybe a bit more.

3) I have read that once you heat treat and then resize, the bullet looses some of its gained hardness - true? Do you size then heat treat? Lead alloys work soften. The current theory seems to be the surface becomes somewhat softer in sizing, the more you size the more it's affected. The best method seems to be to size ASAP and let the boolit harden after sizing. It will take the boolit 1-2 weeks or more to achieve max hardness.

4) How about gascheck bullets, do you go ahead and check them prior to heat treatment? When you size them.

5) When do you lube? Soon after treatment, or do you wait until you get ready to load 'em? (I use an RBCS lube/sizer)Again, ASAP.

6) How long can I store the treated bullets before they begin to soften?Years from what reports I've seen and my own experience. It takes days to harden, but years to soften. I would say it depends ultimately on your alloy, but 2-3 years should lose you no more than a point or two. It may well be safe to use them 10-15 years later, no one I know of has done a long term study.

7) Any advantage in heat treating pistol bullets (9mm, 40S&W, 45ACP)? It depends entirely on the specific barrel. Each is a law unto itself. Some will prefer a nice soft 9 Bhn boolit at 800 fps, other require a harder boolit to feed well and some want a much harder boolit to take the shallow rifling in many auto guns all at the same 800 fps. When you up the speed/pressure it may or may not require a harder boolit In general terms I'd start with straight WW and see what happens. I think fit is far more important than sheer hardness, so make sure it fits right, .001 or.002 over groove size or as large as the throat will handle, and then play with hardness.

I know that I have asked a lot of questions, but I know that there are some of you who have ALL the answers!! Thanks!!

Nobody has ALL the answers, but there are some that THINK they do!:mrgreen:

[dubber123]

I can answer a few. I heat treat at 425° for 1 hour, and quench immediately in cool water. I get around 20-22 Bhn. This is out of straight WW's, and is roughly double what they are un heat treated. (about 11 Bhn before, per LBT tester). Quenching at 450° can sneak you up near 30 Bhn. I check and size as soon as posible, to prevent swaging off much of the hardness. Within a day seems good.

I don't see any advantage in hardening my 45 ACP's, 40 S&W may be different, depending on how fast you are driving them. It's alot of unneeded work for most pistol shooting.

[pdawg_shooter]

I cheat. I use them as cast and air cooled but I paper patch.

[243winxb]

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/faqs/bullet-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.

[243winxb]

Lyman>
Size your bullets but do not lubricate them When i run a bullet into my Lyman 450 dry, it does not go in and out well. Not something i want to do with 500 bullets.

[Bret4207]

Many more casting tips at Lyman, look here>> http://www.lymanproducts.com/lyman/faqs/bullet-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.

According to metallurgist types the antimony won't separate from the lead alloy, but will stay in solution.

[sqlbullet]

It has to do with the size of, and manner in which, the alloyed metals get captured by the lattice. Short version: from as hot as possible while retaining shape, to room temp as fast as possible. The goal is to instantly freeze the molten metals.

I use isotope lead that is an air-cooled bhn of 10.5 to 12. If I drop them straight from the mold into water, using a 700° melt, I get 28-32 bhn. See data here. (http://www.fellingfamily.net/isolead/index.html)

[runfiverun]

i believe with water dropping it pulls antimony closer to the surface,leaving the center softer.
the final hardenss of heat treated boolits is also determined by the temp being allowed to permeate the whole boolit,the temp is also dictated by the amount of tin in the alloy.

[243winxb]

Lyman> When i run a bullet into my Lyman 450 dry, it does not go in and out well. Not something i want to do with 500 bullets.

Lube bullets with RCBS Case lube 2. Size using a Lee push thru sizer. Wash lube off with hot water and 2 drops of Dawn. Dry and tumble lube with Alox.

[243winxb]

Grain-boundary strengthening (or Hall–Petch strengthening) is a method of strengthening materials by changing their average crystallite (grain) size.

As in oven Heat treating, water cooling.

[Burnt Fingers]

Lube bullets with RCBS Case lube 2. Size using a Lee push thru sizer. Was lube off with hot water and 2 drops of Dawn. Dry and tumble lube with Alox.

You just replied to your OWN 12 year old post.

Why?

[243winxb]

To make the information complete. That's why.

Oven Heat Treating - water cooling - hardening , the complete method.