Annealing water dropped bullets

JWFilips

Well-Known Member
Ok I'm having a senior moment ( So I think I may have asked this before)

I have a couple hundred water dropped bullets from COWW alloy + a bit of Lino
They are at about BHN 22

If I put them in a a oven and bring the temp up to 400 deg for about 15 minutes then shut it off until fully cooled will I get the BHN down to 14-15?

The reason why........... I think I have done this before ( With a question to the forum) is I have notations that say that I have done this before: However I can't remember when????
 

Rick

Moderator
Staff member
That is the annealing process but I would recommend an hour in the oven if your goal is to bring them back to the air cooled BHN. You can't make them any softer than the air cooled base alloy.
 

JWFilips

Well-Known Member
Rick,
After reviewing my notes from last summer I see that I tried to anneal 50 22cal bullet in my oven set to 400deg for 1 hour. Then shut it off and let them sit for the rest of the day to cool because I figured I would be safe from "slump"
Because they were small I just laid them on the pan on their sides
They all came out flattened on the sideo_O
But the were softer. Thought 15 minutes would be safer
Jim
 

Brad

Benevolent Overlord and site owner
Staff member
Your oven may not have a really accurate thermostat. Also, most ovens cycle where they go well over the set temp then cool down a bit. This is why I put a PID on my heat treat oven.
Try another test at 375 Jim. It will likely anneal the bullets just fine. May not get as soft but they will be softer. Better yet, they hopefully won't get a flat spot!
 

Rick

Moderator
Staff member
What was the Sn percentage of these bullets? The higher the Sn the lower the melt temp. Next oven thermometers are notoriously inaccurate, I sometimes use three in my convection oven and they never read the same. The dial on ovens are even worse. Crank down the temp 20 degrees or so & use just 2-3 bullets to test for slump.
 

JWFilips

Well-Known Member
Rick & Brad,
Thanks for the above info.
I will try that.
Is it important to stand the bullets on their bases? Or can they be laid in the pan?
Jim
 

Brad

Benevolent Overlord and site owner
Staff member
Depends? If they slump even a tiny bit then laying on their side will show it easily. Standing them won't show the slump as well but also means they won't be affected by a very minor slump.
I heat treat mine laying on their side but I don't go for max hardness either. That means I heat to 400, 425 tops while my alloy isn't likely to slump til, closer to 450. Having a PID controller lets my have better temp control too. No overshoots of temp they give me problems.
 

popper

Well-Known Member
You do have to watch temp for slump, a few boolits is not good for the test as the heat load is changed - unless you use a PID and even then you can get some overtemp swing. According to Felix and me, 10-15 min is good to ANNEAL. Not enough for hardening (WQ) whih does take and hour or so. 10 min cook for coating gets you back to AC hardness.
 
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JWFilips

Well-Known Member
OK I did try a test run of about 10 bullets standing up on the bases.
To be extra careful I set the oven dial to approx 360 deg and turned it on.
it took about 8 minutes to come up to temp and the oven light to go out. at that point I slowly turned up the dial to see where on it's setting the light would come back on.
That is when I found it was near the 425 deg setting!!!! So I cracked to door to get it back down to about 400.

So all in all the bullets were in the oven for only about 20 total and half of them slumped! so I just took the pan out of the oven & let them cool in the air
So I have know idea what the alloy mix is if it is slumping so soon. good thing I didn't put a lot of them in there.
I did test them for hardness and they are down around 14 bhn in that short period of time without the long cool down period. Not sure if they will harden back in a few days

I'm thinking that maybe I can put them in at even a lower setting ( since I really can't control this oven with a PID) for about 15 minutes and hope to get them down even a little in hardness like Popper mentioned
 

Rick

Moderator
Staff member
My CWW with 2% Sn added air cooled runs 12 BHN. You are using CWW with "a bit of lino" added so a BHN of 12-14 is a reasonable expectation. You cannot make them any softer than the what your base alloy is air cooled.

Doesn't matter if you have one bullet or a hundred in the oven as long as they are in there long to completely heat soak throughout.
.
 

popper

Well-Known Member
most of the toaster oven use a bimetal therm. that is NOT in the oven chamber. They will overshoot quite a bit when heating up.
 

fiver

Well-Known Member
I bought a convection oven for BHN changing and for powder coating quite some time back.
I also bought a thermometer to set inside the oven.[like 8 bucks at the china mart]

since I had them and the oven was set up on the table I decided to play around with it a bit.
I found that one end of the oven would heat up higher than the other end by almost 10-f.
and that the air above the tray was hotter than below the tray.

if I fully loaded the tray with 500 bullets it took longer to heat up the oven, it wouldn't get as hot [in the 1/2 hr. I let it run] but it would hold the heat more consistent.
when heating up everything, the cycles would jump the temps up higher and higher [bigger temp jumps] the hotter the oven got.

one thing you can do to help yourself here is to add some mass to the inside of your oven.
a brick or a few flat rocks in the bottom really help.
 

Brad

Benevolent Overlord and site owner
Staff member
I have a small convection oven I got at Menards on sale for 35 bucks or so. I drilled a hole in the side so I could feed a 6" thermocouple thru and let it sit above the rack at least an inch from anything inside the oven. With the oven plugged into the PID and set to max temp I can watch the oven cycle on and off the maintain temp.
 

Dusty Bannister

Well-Known Member
When I do any heat treating, I will turn on the oven and have it come up to full temp and watch or listen for the heating element to click on and glow red. After a few cycles I will put in the bullets and start the timer. When the timer goes off I watch the element and as soon as it shuts off during that heating cycle, I remove the basket of bullets and quench. That gives me the maximum heat setting.

For annealing, you might want to consider preheating the oven and then when the element clycles off, insert your basket or tray of bullets to heat soak and then turn it off after your selected time period has expired and the element shut off. Most of the information I read shows that annealing takes place at lower temps than Heat Treating. And is dependent upon diameter of the bullet to heat through, as well as the alloy involved.

Eventually, as my supply of alloys deplete, I will have to do more HT/Q but not real likely anneal as that would require the removal of lube from the bullets.
 

358156 hp

At large, whereabouts unknown.
most of the toaster oven use a bimetal therm. that is NOT in the oven chamber. They will overshoot quite a bit when heating up.

I ran into this with my convection oven. It has closed ducting into the area the temp controller is, but the heated air from the oven never got within about three inches of the bimetal controller. To add insult to injury, the side chamber retains heat, and after a while the bimetal would get hotter than the actual temp in the oven chamber. Anyway, the bimetal would get hot and start lowering the oven temp. I originally turned the oven on high, and plugged it into the PID with a thermocouple going through the back of the oven. I thought I had a bad thermocouple at first, since I couldn't maintain temps after about 45 minutes but testing with a second thermometer told me what the problem was. Once I figgered out what was really happening I bypassed the bimetal so the oven ran constantly on high temp. The PID did its job, and now I have temp control for the first time. My temp swings like popper mentions also went away.

Bimetal=evil!
 

popper

Well-Known Member
The outer cover of my toaster oven is removed so the bimetal is in open air - I just turn it to max. Toss a cotton towel on top for insulation. Same with the Lee pot, PID control. The oven only gets used for HiTek pistol anymore, hot plate for PC cooking or H.T. Got a big old Al pan I use as a cover to cut down on losses for the hot plate.
 

JWFilips

Well-Known Member
OK I had good success yesterday!
Use my kitchen over ( Electric) Set the contols to 375 deg and put my lead theremometer in it.
When the PRE heated signaled I read the dial and it was 380 deg.
So I boosted the temp up to 385 deg and when it had preheated again dit was about 390 on the dial of the thermometer.
I opened the oven and stuck the pan of bullets in then I waited to hear the heat cycle back up & when I hear the stove click off again I shut off the oven and let it sit for 1.5 hours cooling down
The bhn 22 bullets are now 12 /13 bhn so I call that a big success! As mentioned above, I guess the heating is not as critical if you want to anneal alloy!!!
Thanks for the tips!
 
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Oklahoma Rebel

New Member
good info!! I have about 150 too hard boolits that I was thinking about trying this on.hey popper! Oklahoma rebel here.... just found this sight, so far pretty good!