Heat treating Linotype

[outdoorfan]

Got a small batch to experiement with in the .223. I was wondering if they would HT. Some say it will; others say it won't. I just tested the hardness of some HT'ed boolits. I HT'ed them two days ago at 475 degrees for 1 hour, and very quickly dumped them in 55 degree water. According to my Lee tester, they're right at about 17. Same as the AC'ed ones. In contrast the 2/1 ww/soft that I HT'ed at 500 is about 22.

Was kinda hoping I could make that Lino really hard. I suppose I could mix it 50/50 with ww's and try again.

[bishopgrandpa]

lino will run 20-22 bhn as is. Why would you want any harder?

[fredj338]

If it has antimony in it, it will heat treat. Follow LASC guide for heat treating & they should harden up a bit more than BHN22. You need to give them a few days to harden completely. http://www.lasc.us/HeatTreat.htm

[outdoorfan]

lino will run 20-22 bhn as is. Why would you want any harder?


Maybe I don't need them harder, but I want to experiment to find out.

Also, I just stated that I'm getting around 17, not 20-22.

[outdoorfan]

If it has antimony in it, it will heat treat. Follow LASC guide for heat treating & they should harden up a bit more than BHN22. You need to give them a few days to harden completely. http://www.lasc.us/HeatTreat.htm

Maybe they need more time to harden up, but I don't think so. The more antimony, the faster they should harden up. Mine are simply not hardening up. And, as far as I know, there is nothing wrong with my method of HT'ing.

[jhalcott]

ODF, you shoul first find out how hot they need to get to "slump". THEN heat them up to a few degrees below this temperature. You should then drop the bullets into VERY cold water. Immediately after removing from the oven is best. You CAN get BHN's of over 30 doing this. BUT it is only a SURFACE hardening, not a thorough, thru and thru deal.Bullets this hard will NOT "bump up" to fill the bore. To prevent leading due to this condition, size,but not lube the bullets before heat treating. I have had decent results with acww and aclino alloys in my .223. You must think you NEED high velocity to contemplate HTing .223 bullets.

[outdoorfan]

ODF, you shoul first find out how hot they need to get to "slump". THEN heat them up to a few degrees below this temperature. You should then drop the bullets into VERY cold water. Immediately after removing from the oven is best. You CAN get BHN's of over 30 doing this. BUT it is only a SURFACE hardening, not a thorough, thru and thru deal.Bullets this hard will NOT "bump up" to fill the bore. To prevent leading due to this condition, size,but not lube the bullets before heat treating. I have had decent results with acww and aclino alloys in my .223. You must think you NEED high velocity to contemplate HTing .223 bullets.

Yeah, actually, I would like to get over 2000 fps, which is about where I'm stuck at right now.

I heated them up 'till they slumped; then backed off 25 degrees. 475 degrees right out of the oven, 2-3 seconds into 55 degree water. I don't think I'm lacking anything here. Just reporting my observations. I'll check the hardness again in a couple of days.

[felix]

Linotype, or any other completely "satisfied" alloy, will not heat treat. An alloy that is satisfied is one that all the elements have a perfect fit within another, as in perfectly married. You can tell this in lead alloys by the way the alloy freezes. If there is no slush stage, everybody within is married happily. It takes a villain, like more antimony, less tin, or some foreign monster like arsenic or bismuth to cause havoc during the cooling stage. ... felix

[sqlbullet]

Felix nailed it.

I heat treat the isotope lead I get. I water drop from the mold into water that is just above freezing. I get a BHN of right around 30 this way. This is WAY too hard for my 10mm, so I now air cool.

My understanding of the hardness uniformity is the opposite of what jhalcott posts above. Lead/antimony mixes will have surface issues if no or not enough tin is present due to antimony migration in the matrix during slow cooling. The faster you cool, the less migration, and the more uniform the hardness. I can't find references quickly supporting either position, and my mind isn't what it used to be.

[outdoorfan]

Thanks, gentlemen!

[fredj338]

Yeah, actually, I would like to get over 2000 fps, which is about where I'm stuck at right now.

I heated them up 'till they slumped; then backed off 25 degrees. 475 degrees right out of the oven, 2-3 seconds into 55 degree water. I don't think I'm lacking anything here. Just reporting my observations. I'll check the hardness again in a couple of days.

Try leaving them in colder water for several minutes, then check BHN in 2 days. I water drop ww & can get around BHN20. I understand arsnic in lead shot aids in heat treating & lino lacks this. Maybe the addition of some hardened lead shot?

[Bass Ackward]

Tin is the enemy to heat treating. Antimony will bind vastly better to tin than to lead which is why it won't HT unless you have higher temperature. Tin produces a better balanced bullet as a result of more even dispersion.

But if you are lower in tin percentage than true lino, then you don't have lino. 17 BHN is depleted lino. This is about the same as WW from the 60s, at 9% antimony and no tin. Why you didn't HT is that you need to add a touch of arsenic. Arsenic is a catalyst that allows antimony to separate and expand even if it is bonded to tin. Arsenic can be found in chilled shot of Magnum grade. The smaller the size, the more the content. Do not exceed @ .01%.

[leadman]

I shot the Lyman 45gr. RN in the 223 and 22K Hornet with WW with a little lino in it and WQ to 3,000fps. Yes, accuracy fell off after 2,600 to 2,700 fps and there were signs of lead in the bore. One pass with a brush cleaned it out.
My varmint load in the 22k Hornet is around 2,500 fps with the same alloy. No leading and very good accuracy.
I have used pure lino, but if you shoot small animals with it there is not much left. I even downloaded to 1,700 fps. Still explosive.

[anachronism]

Add about 10% of magnum (not chilled) shot to your linotype. This should give you enough arsenic to heat-treat.

[454PB]

I mix 1 part monotype to 2 parts pure lead and water drop. These test 27 BHN after two weeks.

[runfiverun]

if i was gonna do what your are trying i'd go with 50-50 ww's and your lino then heat treat.
the heat treating allows the heat to permeate the entire boolit without slumping it and the higher you can get the heat the harder they will get ny lowering the tin content you can up the hardness,dumping them in the water is just like dropping from the mold only the whole batch is at a consistent temperature,when they hit the water and the whole boolit is at this temp.
pick and choose through your little 22's carefully then use your culls to determine the slumping temp of the batch. and back the oven down below that temp by about 15*.

[outdoorfan]

Before I started casting I did A LOT of reading on various casting processes, heat treating being one of them. The comments that were predominent in my original research was that lino would not ht due to not having arsenic in it. But then I kept hearing several people on various forums say that it's antimony that does the trick, and that arsenic is just to give it that "extra touch".

I posted a question awhile back asking whether lino would ht or not. Didn't get much for responses. IMO, not too many people seem to know. So, that's why I tried it for myself. I think guys like Bass and Felix understand this, and a lot of other people don't seem to.

I'm a little puzzled at why my lino boolits are only registering 17 bhn. Could be my Lee tester isn't exact. Could be there's no (or very little) tin in it, but they were filling out quite well with sharp corners, etc.

[felix]

Just test for a slush stage. Repeating, a fully married alloy will have none. Fully married, heat treating is a waste of time, and BHN is 22. If not, your measuring device or your method of using it is off by that certain percentage. ... felix

[GabbyM]

I can't test 22 caliber bullets to well in my Seco tester. Just to small a pill.
You may try casting a larger bullet from your alloy then testing that one. I'd about bet your BHN will read higher. Those little 22's just chrush. 17 BHN is hard enough for 22's anyway IMHO.

[Lutzy48]

Check your tester against some pure lead to see what you get. I made my own tester similar to the Lee unit. Calibrated it with an electronic fish scale. The LT I have tested to be about 20 BNH.

[outdoorfan]

Just test for a slush stage. Repeating, a fully married alloy will have none. Fully married, heat treating is a waste of time, and BHN is 22. If not, your measuring device or your method of using it is off by that certain percentage. ... felix

The "slush stage". I'm assuming that's when typical soft lead or ww alloy will harden, but not get really hard yet for a few more seconds. OTOH, I saw that when using lino, when the sprue changed color it was immediately very hard.

[outdoorfan]

I think the tester is okay, because I've tested soft lead at 6-7, my 2/1 ww/soft mix at around 9.5, ht treated 2/1 in my .30's at around 24-26. It could be the .22 pill is too small, like was already mentioned. Maybe I'll try filing a flatter spot on it.

[felix]

No, determine slush stage using lead in the pot after turning off the power. Should be LIQUID, and then SOLID in what seems like a flash in time. See if a fork, stick, etc. will penetrate the "solid" immediately upon a noticeable change. If penetration, that's slush. If you got some, you ain't got lino. ... felix

[outdoorfan]

No, determine slush stage using lead in the pot after turning off the power. Should be LIQUID, and then SOLID in what seems like a flash in time. See if a fork, stick, etc. will penetrate the "solid" immediately upon a noticeable change. If penetration, that's slush. If you got some, you ain't got lino. ... felix

Ok, thanks for the explanation.

[Lutzy48]

Outdoorfan,

The BHN for lead is 5.0. If you tested it at 6-7, I would guess that your LT probably has more lead in it than usual.

[outdoorfan]

Outdoorfan,

The BHN for lead is 5.0. If you tested it at 6-7, I would guess that your LT probably has more lead in it than usual.

On the soft lead, I was going off of my memory, and I'm not as sure about that reading as I am with the other ones that I posted. And it may have been pure, but I'm not sure. The chart that is included with my Lee tester only goes to 8 bhn (.079 cavity). I just measured an egg sinker (Danielson-.5 oz/size 8) at .105 cavity. Not sure what that equates to in bhn, but it must be considerably under 8. Maybe 5.5-6, or so?

[leftiye]

As B.A. said tin is your enemy when heat treating. The less tin (down to 1/2 percent, the better it heat treats. Magnum shot is about 5% antimony 1/2% tin. It will heat treat by itself (without mixing with anything) to BHN42.

[outdoorfan]

It must have some arsenic in it too, right?

[runfiverun]

most shot does, it's what makes it go round through creating surface tension.

[leftiye]

Arsenic helps, no "must" involved though. (Isn't must what they make wine out of?)