Heat treating

[lead chucker]

If a guy heat treats a bullet at 450 for an hour and quench will that bullet be as hard as a bullet heat treated at same temp for two hours and quenched?

[Wolfer]

I think so. But I'm not sure. My only experience with heat treating was the other way, 1 hour @ 450 then shut the oven off and let them cool off real slow. Come out as soft as first cast.
I had a cap and ball pistol and the only lead I had was WW. They would load ok when fresh but after a month or so I couldn't get them in the gun.

[MT Gianni]

The heat needs to reach the core. If you are shooting 55 gr 22 cal boolits it may do so in 20 minutes, 500+ gr 45 cal might take a full hour. Once the core is @ 450F a longer time only wastes heat.

[LeadBrain]

+1 MT Gianni

I read somewhere that approx 90-95% of your max Hardness is achieved within 30 min at 450 deg for most bullets and that any more than 30-35 mins or the time for the core to reach 450 degs (time may increase or decrease due to several factors such as # of bullets, size of bullets, Preheating of oven, ect) gave very little increase in hardness. The energy cost to hardness increase ratio goes way down.

[runfiverun]

see post number three.

an hour is generally enough for anything.
the key is to get it out and into the cold water asap.
you do the whole batch the same thing for uniformity, so if you go ten minutes less [or whatever] write it down for the next batch.

[LeadBrain]

Here is an excellent write up on heat treating- http://www.lasc.us/HeatTreat.htm

[remy3424]

that is a good article....thanks

[popper]

I put the base of a 30 cal 165 gr on a 450 deg hot plate. The nose was over 212 deg within a minute.

[dubber123]

And make sure to get a separate thermometer. Try it in different areas of your oven. You will likely find hot spots, or areas that don't maintain the same heat as others. In mine, I had to use a tin blocker over the lower element, and use the top rack to get consistant temps throughout the heat cycles. Don't trust the temps on the knobs. My GE went over 500* when set to 450. I ruined 2 hours worth of casting the first time I used it. :(

[Frank]

I get my heat treating from water dropping. I get bullets > BH 30 no problem. My bullets are even low antimony and they still come out hard. I think it's because they are the highest temp they can be when they come out of my mold. I tried oven heat treating. The oven now collects dust on my shelf.

[Shuz]

From what I've read, and from personal experience, on the subject of heat treating, oven heat treating gives more uniform results, boolit to boolit, than water dropping from the mould.
One of the best devices I've found is a discarded, but still functional, toaster-oven. They are small enuf to maintain an even temperature throughout, yet big enuf to treat several hunnert boolits at a time. I use a separate oven thermometer to insure my batches reach 475 deg for at least 30 min. and then dump the hot boolits in a large bucket that its right beneath the oven. When I'm done, I unplug the oven and it's all set for the next batch. Once set, I never muck with the oven temp thermostat...they are just too imprecise.

[Frank]

Shuz:

From what I've read, and from personal experience, on the subject of heat treating, oven heat treating gives more uniform results, boolit to boolit, than water dropping from the mould.
One of the best devices I've found is a discarded, but still functional, toaster-oven. They are small enuf to maintain an even temperature throughout, yet big enuf to treat several hunnert boolits at a time. I use a separate oven thermometer to insure my batches reach 475 deg for at least 30 min. and then dump the hot boolits in a large bucket that its right beneath the oven. When I'm done, I unplug the oven and it's all set for the next batch. Once set, I never muck with the oven temp thermostat...they are just too imprecise.
But look at the extra trouble to get some kind of "evenness" that maybe you already have. So do you install the gas checks on first? What happens when you used dish soap to size and put them on and put them in the oven. Now you've created a popcorn machine. Pop, pop! The GC's get removed. Or maybe you sized the bullets already without checks, so now your hard bullets will need to go into the sizer, another step. Sorry, but I've tried it and the Cuisinart toaster oven is sitting on the shelf. But I would like to see what kind of results on the target those who are benefiting from this oven heat treating technique. Remember, there are hundreds of ways to skin a cat.

[popper]

From the research I can find, Frank is correct, the melt is above the freeze temp, stays there in a HOT mold and drops when quenched in water. The colder the water, the more of the CB gets hardened, it cools from outside in, more Pb-Sb-Sn gets frozen. Now if a CB gets stuck in one half, it cools slower on one side making a lopsided CB, hardness wise. Hardening is a time thing, so some 'freezing' is occurring at room temp. Some of the Sn reforms as solid tin, thus age softening. As is soluble in Sb-Pb so it 'breaks' up the column lattice of the Sb to make a harder but less brittle structure. S also 'breaks' up the lattice, but is insoluble in PB-SB-Sn. As and S form a crystal half the hardness of diamonds, actually a form of galena. Commercial MetGlass, a hard/tough iron material is made by heating and then cooing at >1000 C/sec. Oven HT should give more consistent results(leave the GC off), but is a separate step. Do what works for you.

[Shuz]

Shuz:

But look at the extra trouble to get some kind of "evenness" that maybe you already have. So do you install the gas checks on first? What happens when you used dish soap to size and put them on and put them in the oven. Now you've created a popcorn machine. Pop, pop! The GC's get removed. Or maybe you sized the bullets already without checks, so now your hard bullets will need to go into the sizer, another step. Sorry, but I've tried it and the Cuisinart toaster oven is sitting on the shelf. But I would like to see what kind of results on the target those who are benefiting from this oven heat treating technique. Remember, there are hundreds of ways to skin a cat.

Frank--I size the boolits first and then HT. When I get them out of HT I install the gas check and then apply the lube.
I'm not saying that oven heat treating is the "only" way to heat treat, but at least it removes the hardness variability concerns you have when water quenching from a mould and boolit(s) stick in one side of the mould until you tap until it frees and falls into the water; perhaps many seconds after it's "brothers".

[Frank]

Shuz:

I size the boolits first and then HT. When I get them out of HT I install the gas check and then apply the lube.
Great. What lube do you use when you size them?

[Frank]

Fryxell's article:

Bullets destined for heat treating should be sized without lube and gas checked before they are heat treated, not after.
How do you do that?

[Pat I.]

I size before heat treating with a Lee push through minus any lube and gas check with no problems at all. I've had problems if I apply the gas check before heat treating though. It melted the shank around the check for some reason.

[felix]

Pat I is correct!!!! ... felix

[popper]

+1 for Pat and Felix. you can use wax or case lube first and wash it off, if sizing down a lot.

[Shuz]

Shuz:

Great. What lube do you use when you size them?

I use my normal lubrisizer without any pressure on the reservoir so I don't get any lube in the grooves, but there is evidently sufficient lube still in the die, because they don't stick.

[Frank]

I'll stick to water dropping. Remember, any slumping and it's bye, bye accuracy.

[MT Gianni]

I put the base of a 30 cal 165 gr on a 450 deg hot plate. The nose was over 212 deg within a minute.

Popper, heat transfer through the skin or outside of metal will be different than through air. I would wager that your bases will slump long before your center is up to temp.

[Frank]

Pat I:

I've had problems if I apply the gas check before heat treating though. It melted the shank around the check for some reason.
Mt Gianni:

Popper, heat transfer through the skin or outside of metal will be different than through air. I would wager that your bases will slump long before your center is up to temp.
Maybe that's what happened with Pat I.

[popper]

MT Gianni - no, they didn't slump, some bases melted. I was testing the thermal conductivity of my CBs. The ones with good bases shot OK. The ones I oven HT and dropped in ice water are more consistent and really hard. I really had to squeeze on my vice-grip hardness tester. Rotational shear force was a lot higher than plain WD.

[Frank]

How do you know it didn't slump. If a misaligned lubesizer can mess up a bullet by a hair, then what can you judge by your naked eye?

[popper]

Frank - I don't know if there was slump. I don't have the equipment to even know if my sizer misshapes the CB by a thou, or what the bbl does to it. Not sure I even know what the slump term means as used on this BB. If like concrete, it is a change in diam. vs length, with force applied parallel to the length. If HT on their side they would get out of round. Best i can say is when run through the sizer and observed under a 20x loop, the lube groove edges look the same all around the diam of the CB. Educate me please, I'm listening.

[huntrick64]

I have followed the LASC article referenced above for several years and it has been spot on. I have targeted BHNs from 12 up to 25 with predictable results. It has been my practice to cook each batch 1 hour regardless of the bullet size and just vary the temp to vary the final bhn. I quench immediately in cool water (just straight cold tap water). I also use a convection oven (just don't tell my wife). I size the day after I quench so they are harder than without heat treatment but not as hard as waiting a few days to do them. I was amazed how much pressure it took to size a BHN 25 bullet vs a bhn 12 bullet using a Lee sizing die. I have treated my 180 grain .40 for the 40 s&w to bhn 25 and my 285 grain 45 up to 18. Have done 357 bullets up to 25 as well, but never found a load in my guns than needed that hard of a bullet.

Since I have worked on my guns to ensure proper bullet fit through the throats, the cone, and the barrel, I have been able to stop heat treating all together and shoot 12 bhn (straight ww) for my magnum loads and drop down to bhn of 9 (50/50 - ww/pb) for my moderate loads. By moderate I mean that 285 grain 45 at about 1100 fps. Zero leading! My biggest offender has been the constriction where the barrel screws in. Followed that by cutting my forcing cone to 11 degrees and then making sure my throats were .0005 over my bullet diameter. If you think I measured that your crazy, I simply lapped them out until I could push my sized bullets with light finger pressure.

Regarding slumping - Just test it with a few bullets first before you put the whole batch in there. I have went up to 465 F for an hour with my wheel weights (no tin added) and never had any slumping. Your results my vary.

[Frank]

Popper:

Best i can say is when run through the sizer and observed under a 20x loop, the lube groove edges look the same all around the diam of the CB. Educate me please, I'm listening.
We're just talking, not fighting like editors in a newsroom. You're right. The lube groove edges give you some kind of a picture. And you can keep the nut and punch loose, put the bullet in first, then tighten it. I feel good about lubesizer mechanical alignment. But looking through the little window and seeing my bullets in there coming up to temp does make me a little worried.

huntrick64:
Your whole post very informative. I have found hardness up to 27 is smooth through the Lee die. 30 and above it gets hard to push through.

[blackthorn]

huntrick64---Can I take it that your very interesting post refers to bullets treated to various levels of BHN from the same batch of alloy?

[popper]

Frank - I cheat, with a thermocouple in the nose of a bullet! Toaster oven (convection type) air temp varies about 50 deg, CB temp stabilizes real well.
huntrick64 - I did the chilled water thing to get hardness through as much of the CB as possible, not just the outside layer.

[huntrick64]

Blackthorn --- My alloys were not from the same batch; however during the time I was heat treating (about 2 years) I was getting my wheel weights from the same place and they were modern weights in that every two months I would pick up another 5 gal bucket full (ah, the good ole days). I would pick out the stick-on weights and zinc weights and considered everything else in the bucket as alloy, flux, or dross. Valve stems do work as flux, but they stink and burn quite a while. I did test each batch about two weeks after I poured the ingots and they always came in at 11-12 BHN without heat treatment.

Here is an interesting thing I found while testing various BHNs out of my 40S&W. Using the same charge of power pistol (I don't remember off hand what that was but it was toward the top end) I started at 12 bhn and went 15, 18, 21, and 25. 18 and 25 bhn shot the best groups and 12, 15 and 21 bhn shot the worst groups. No leading using the 25 bhn so that is what I went with. I just thought it interesting that the group tightened up then loosened up then tightened up again as you went up in bhn. I shot about 50 of each bhn so I felt it wasn't just me. I tried to figure out why this happened and quickly came to the conclusion that it didn't really matter. What mattered was that for that load of power pistol, in that gun, bhn 25 was the right hardness.

Somethings are better off left unknown: Like a thermos - It keeps hot stuff hot in the winter, and it keeps cold stuff cold in the summer! How does it know?

[Frank]

popper:

Frank - I cheat, with a thermocouple in the nose of a bullet! Toaster oven (convection type) air temp varies about 50 deg, CB temp stabilizes real well.
One idea. One can always run them through the sizer again. If they are slumped (leaning) then it would be visible on the skin like you said.