Oven Heat-Treating......Just how flexible?

[BrushBuster]

I've pretty well settled on the method of heat-treating my boolits in the oven. However, I happen to have one of those earlier Marlin rifles that have the very shallow 16 groove lands (1957 Micro-Groove) and I'd like to do some experimenting with various hardness levels to find the optimum for this bbl. The hardest boolit that I have shot so far has been oven heated to 450f for 30 minutes and then quickly dumped into ice-water. This one performed very well, but I only know it was HARD, not the actual BHN.

What I would like to try is a range of softer boolits, and was wondering what the flexibility of the oven method is? What can I vary? The oven temp. and/or time factor, or the water bath temperature? Anybody fooled around with this before? :confused:
Thanks,
BrushBuster

[Bass Ackward]

What I would like to try is a range of softer boolits, and was wondering what the flexibility of the oven method is? What can I vary? The oven temp. and/or time factor, or the water bath temperature? Anybody fooled around with this before? :confused:
Thanks,
BrushBuster

BB,

You sure can change BHN by changing temperature. That's why you see the range listed as say 20 to 35 BHN. But it is a trial and error method that depends on your mix and your procedure. Using straight WW, it is hard to get below 20 without adding some pure lead. And once you cross the temperature threshold of about 400 degrees, you drop to air cooled hardness levels. So your quenching speed at lower temperatures is more critical than top temperature levels where you have more room to wiggle.

The technique can be remarkably difficult to reproduce a consistent hardness. If you are successful, you start to lose hardness over the course of a year. So large batch storage is difficult unless you freeze them in a freezer which is what I do for the few bullets I need to match this level.

If you mix straight WW with about 1/3 pure lead and HT at 450 for about an hour you can end up with bullets from 16 - 18 BHN pretty reliably. This will remain for about 3 months unless you stick them in a freezer as above. Just to get you started.

[stocker]

BB - If you are referring to the boolits I sent you they were 1 hour at 450 not 30 minutes. Quenching was as close to immediate as you can get. They are hard puppies aren't they?

[454PB]

I recently came across some 429244 boolits that I had heat treated over 20 years ago. I didn't test them with anything more sophisticated than my thumbnail, but they are way harder than pure linotype.

[BrushBuster]

BB - If you are referring to the boolits I sent you they were 1 hour at 450 not 30 minutes. Quenching was as close to immediate as you can get. They are hard puppies aren't they?

Yes Stocker, 60 minutes was what you said. They are hard, and they also shoot good. We also know that they don't shatter or fracture when subjected to the hammer test, so they probably represent the hardest level that I need to go to. Just a little curious if a little more obturation might make for an even better boolit for this particular bbl. Kind of difficult for me to visualize what the Micro-Groove really likes?

[stocker]

BB: I usually heat treat so many at a time , often more than a thousand in a couple different cals. that I use the longer heat time assuming it takes a little longer for a batch to come to temperature equally. Tkaes longer for a big roast to reach internal temperature than a small one as a comparison.

A shorter heat time might indeed give a different result but I can't confirm that as they are all done the same except for the ones I don't temper at all.

[44man]

Heat treating boolits seems like so much trouble and work. Are you sure water dropped boolits are not as good? I have never figured out how a batch of boolits heated to the point of almost slumping can be moved and dumped in cold water without damage. Seems to me a large basket is needed that can be submerged without moving any boolits.

[BrushBuster]

44man, what appeals to me about the oven method is that I can focus on casting good boolits and then later heat-treat as many as I want in batches(after installing gas-checks and sizing). This method also allows experiments in hardness levels which was the basis for my post. I can only say that Stockers boolits are excellent, and lack nothing in consistency. Heat-treating a thousand boolits at once doesn't sound like too much trouble to me, especially if it works! Stocker uses a large modified steel parts washing tray and dresses appropriately for the unavoidable surge of steam that goes with the process.

Bass said: "If you mix straight WW with about 1/3 pure lead and HT at 450 for about an hour you can end up with bullets from 16 - 18 BHN pretty reliably. "

Bass, what about the 3% Tin content that we have discussed recently. Would I still try to maintain it in this 33% pure lead-WW alloy or forgo it to obtain a softer boolit? This sounds like something I'd like to try.
Brushy

[jballs918]

i was thinking about this and i thought that a nice little toaster oven would work well. you know throw in a small batch while casting. i should work ok

[stocker]

I checked ours and found that the heat cycle was much too broad with emphasis on the high side whereby bullets might slump. There was a 70 degree swing from low end to high end. Our excellent kitchen stove oven barely makes a 20 degree (+/- 10 degrees) swing. Other toaster ovens may be more accurate than ours, I don't know.

[waksupi]

I've used the toaster oven, varying the temps by 25 degree increments. I got a very good repeatable spread of hardnesses.

[BrushBuster]

I've used the toaster oven, varying the temps by 25 degree increments. I got a very good repeatable spread of hardnesses.

Thanks, waksupi, that's encouraging and simple! Getting to where I want to be, might be easier than I thought.:-D

[stocker]

BB- I think that little (remember you sent me pictures) lady has you terrified. And you a big strong man. These guys may think all Canucks are like that. Assert yourself and demand equal time at the stove. Failing that there are a bunch of old cabins up the lake you can shoot the packrats out of and call home.

[drinks]

Waksupi;
Did you publish your complete results on different temperatures and the resulting hardnesses?
If so, I missed it, could you direct me to a thread?
Don

[KYCaster]

Brushy: I've never tried heat treating boolits so everything I say is just a guess, but......it seems to me, you should be able to anneal hardened boolits and get the results you're looking for.

I think I'd start at 125* for one hour, two hours and three hours, and see if they soften any, then based on results of that trial, change temp. and time as results indicate.

Should be easy enough to try and the results may be very interesting.

Jerry

[felix]

Jerry, that won't work. Anything under 300 degrees is a speed-up temperature. Best to go to 450 or 425, wait an hour, and slowly drop the temp to make the boolits softer. ... felix

[BrushBuster]

BB- I think that little (remember you sent me pictures) lady has you terrified. And you a big strong man. These guys may think all Canucks are like that. Assert yourself and demand equal time at the stove. Failing that there are a bunch of old cabins up the lake you can shoot the packrats out of and call home.

Yeah, it did take awhile for me to get the ok. to use the new oven. Now when I tell her about the next step, she's gonna say " YOUR GOING TO DO WHAT IN MY SINK"!!! Who told you I was big and strong? [smilie=l:

[stocker]

felix : Thank you , I think that tells us where to go next. Glad to heve a smart feller amongst us.

[454PB]

I used a toaster oven, slowly raising the temperature until several culled boolits began to slump, then drop the thermostat 25 degrees. The boolits were presized and gas checked. The heat actually anneals the gas checks.

I experimented with varying amounts of time and found the most consistent results by leaving them at temperature for 2 hours. I kept track of thermostat settings and made marks on the scale for future reference. 2 hours sounds like a long time, but I feel it was necessary considering the temperature fluctuations in a small, relatively cheap toaster oven.

The toaster oven I used would hold several hundred .44 caliber boolits easily. I got good at transfering them from the oven into cold water, it took about 5 seconds.

These were made up for use in a .444 Marlin, and I was able to shoot 2" groups at a hundred consistantly.

[waksupi]

I think an hour is plenty, really. The secret of using the toaster oven, is to watch the little light. Take the bullets out when it cycles off, and you will be at the highest temperature.

Don, I think I did post them on here, but wouldn't have a clue to what thread they would be on. Remind me on the weekend, and I will try to dig out the info. I believe I have it on the wall upstairs somewhere, in my highly organized filing system. All of my readings were from a Cabin Tree tester, and I do believe I did a transfer of the numbers to Bn.

[KYCaster]

Felix: I don't understand what you mean by "speed-up" temp. By slow cooling from 400-450 you'd get a dead soft boolit. I think by annealing the oven treated boolits, you could get most any hardness you want between oven treated and ACWW. Results should be pretty consistant and repeatable.....sounds like it should work, anyway.

I guess I'll just have to try it and see. Just what I need, another project! Oh, well, I've been wanting to try some heat treated boolits in the 35Rem. MG and I just got a RCBS 35-200-FN mold. Looks like its time to do some 'sperimentin'.

Jerry

[Cayoot]

[QUOTE=454PB
The toaster oven I used would hold several hundred .44 caliber boolits easily. I got good at transfering them from the oven into cold water, it took about 5 seconds.
[/QUOTE]

So what was your method of transfering? I'm always worried about bumping and distorting the boolits by dumping them into the water (afraid they will bump into each other or the edge of the pan when I dump them out.

What nuggets of wisdom can you offer on this?

[Bass Ackward]

Bass, what about the 3% Tin content that we have discussed recently. Would I still try to maintain it in this 33% pure lead-WW alloy or forgo it to obtain a softer boolit? This sounds like something I'd like to try.
Brushy


BB,

Same strategy. I just simply refer to WW as a standard. Although you actually change it when you add tin or anything else. So whenever you see me talk about WW, I am refering to a mix that includes some antimony that results in an air cooled hardness of 11-14 BHN. The tin is my aid for a tougher, more ductile hunting bullet.

Today's WW mixes will vary from @ 2-4 percent depending of how many you get from each manufacturer and how much of the pure lead ones get through. I feel pretty comfortable that I will not go over the antimony content of my WWs if I hold tin at 2%. And none of my bullets have ever broken up during expansion testing. This is easy in my mind because all of my WW is free anyway. So tin is a modest expense for me. Could be that I could change that to 1% today. Old habbits ..........

Added: But when you add more pure lead you are diluting the antomony content which makes a more ductile bullet anyway. So you may not need any tin for that purpose. Who knows? You will just have to try it.

[waksupi]

I am also concerned about bullet damage on the transfer. What I do, is pull the little tray from the broiller oven, and immediately drop the tray and bullets directly into a bucket of water. Seems to work OK to me.

[stocker]

As Brush Buster mentioned I use a heavy duty parts washing basket that is made from perforated steel of fairly heavy gauge. It's about 16" diameter and several inches deep. I don't dump the boolits. Basket and boolits go together into the quench. There is enough live steam generated that you must protect your hands, wrists and lower arms and face from scalding. I have removable steel dividers for the basket to segregate different boolits.

[drinks]

Waksupi;
That would be appreciated, I have been threatening to run a test series, but it would take at least 2 days to do it right.
Don

[BABore]

I do my oven heat treating in a couple of nice trays I built out of 1/2" x 6" x 6" aluminum. Put in 52 blind holes with a 1/2" end mill, 1/4" deep. Added a loop handle out of stainless.

I use a standard (Jenair) kitchten oven for my heat treating. With straight WW's I HT at 435 F for 60 minutes then quench in a sinkfull of cold tap water. After a day or two hardness is 28-30 Bhn. I've tried water dropping the WW bullets, but get a bit more inconsistency, like 26-30 Bhn. Larger bullets show a higher variance than the smaller ones. I can understand why you get such a spread when WD bullets because of all of the variables involved.

Lately I have done some research on annealing oven heat treated WW bullets. Starting with OHTWW bullets that were several days old I put them in the oven for 60 minutes, then turned off the heat. They were removed when cold. Working in 25 F increments, I established data points of 15, 18, 21, 23, and 25 Bhn. Temperature ranges were 250 to 325 F. I'm currently working on a larger scale batch for accuracy and penetration tests. Going to be a long project. On one test batch of WDWW's I did find that the hardened bullets going in, with some variation, showed almost zero variation once annealed. Could be a good thing for production speed and to save a step. I don't think annealing would be sucessful in a small toaster oven as they're not as well insulated as a normal oven. The temperature would likely drop too fast for a proper annealing.

I've also played around with alloying WW's with pure lead as recommended by another well known member. The ultimate hardness can be controlled pretty well by varying the Pb amount. A WD or OHT hardness of 18 -24 Bhn can be achieved easily. Expansion and and ductility are also realized with this alloying.

[BrushBuster]

So many great responses to this post that I just have to give thanks. It always comes back to getting busy and try it out yourself, but these contributions do put one on track and save time.

I've already experienced better shooting with CB's than I ever did with jacketed, and been a while since I've been this enthused. I'm hooked!

Joking aside, my missus supports my boolit projects, and as long as I don't abuse kitchen privileges, I should be allright. Something about keeps me out of mischief? [smilie=1:
Brushy

[Greg]

What I would like to try is a range of softer boolits, and was wondering what the flexibility of the oven method is? What can I vary? The oven temp. and/or time factor, or the water bath temperature? Anybody fooled around with this before? :confused:
Thanks,
BrushBuster

This is my method for heat treating boolits with my alloys and oven. Your results may vary.

Bring the oven up to temperature, then place the sized bullets in the oven, and the set the timer for 1hr Quench in ice water, let steep for 30 minutes. Towel or air dry, then lube. If you notice, the gas check will turn on the boolit base.


Wheel Weights:

Wheel weights SLUMP when heat treated at 485º


Results:

Cast at 680º Heat Treated at 400º for 30minutes for a BHN of @ 12 after 72 hours.

Cast at 680º Heat Treated at 450º for 30minutes for a BHN of @ 14-15 after 72 hours.

Cast at 740º Heat Treated at 465º for 1 hour for a BHN of @ 20-22 after 72 hours.


92 - 6 - 2 Alloy: Magnum shot with 2% tin added...


Results:

Cast at 740º Heat Treated at 400º for 1 hour for a BHN of @ 12-13 after 72 hours.

Cast at 740º Heat Treated at 465º for 30minutes for a BHN of @ 16-17 after 72 hours.

Cast at 740º Heat Treated at 465º for 1 hour for a BHN of @ 21-22 after 72 hours.




50 : 50 Alloy: equal parts by weight of pure lead and wheel weights...

I heated the 50 : 50 alloy to 500º, it never did SLUMP.

Results:

Cast at 740ºand air cooled, for a BHN of @ 6 after 72 hours.

Cast at 740º Heat Treated at 430º for 30minutes for a BHN of @ 15-16 after 72 hours.

Cast at 740º Heat Treated at 465º for 30minutes for a BHN of @ 18-19 after 72 hours.


Remember, these temperatures are for the electric oven that I use. I normally do a smaller batch and quench in a plastic 2 gallon bucket. I add ice to the quench bucket to appease my superstitions. for large batches (seldom) I use a five gallon bucket.

[KYCaster]

BABore: Your tests confirm what I was just guessing at. Saved me a LOT of work, thanks. The only thing that surprised me is the 250-325 temps. I was guessing a little less than half the melting temp. would be required.

Jerry