Heat treating cast bullets

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  • Last Post 15 March 2013
R Dupraz posted this 17 January 2013

I have had this old Rem.722 .257 Roberts for quite a while now and it has proven to be a pretty fine shooter with jacketed. So,decided to see if it would be worthwhile fiddleing with it so that I might use it in the hunter class and some postals this summer.

One bullet that I was hoping would work was the RCBS 257-120 but according to the Greenhill tables, it was out of the upper limits for both weight and length in a 10” twist. A freind happened to have this mould and lent it to me to try. I'm figuring that if it fit and it could be pushed fast enough, it may work ok.

To make a long story short, I shot some at fifty yds cast from alloy of about 11-12 BHN and loaded with 14,15 and 16 grains of IMR 4227. Not so good, no groups to speak of, 16 grns was scattered.

So, I'm thinking, alloy could be too soft, why not try heat treating. So I cast some more and dropped them into a bucket of water, then let them age overnite. The BNH inceased to about 15.

Yesterday, I shot the same series of loads, again at fifty yds. Below are the results. The five shot group with 16 grns of 4227 were similar but these two targets were the best of the lot.

Only fifty yds to be sure but it appears that this bullet, heat treated, might have some possibilities. The real test will to be at the 200 yd. line of course.

In light of the above long winded tribe, the question is, after heat treating by dropping in water, do I have to size them right away or can I store them and size them as I need them. Seems to me I have read something about this destroying the hardness of the bullet if sized later. This method seems to be more convenient for me than to use the oven quench later.

Another challenge, the quest continues.........

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Michael K posted this 17 January 2013

I have used this bullet cast from my WW/lino mix in my M77 25-06 with good success using between 18.0 to 22.0grs of 5744, WLR and LBT blue. The better 5-shot 100yd groups have been just under an inch, the others are rarely over 1 3/4". Velocities with 18grs are 1630fps up to 1950 with 22grs. Going higher has lead to the groups progressively getting larger and morphing into patterns.

Thanks for this post, I too have pondered heat treating or water quenching this bullet. Looking forward to seeing what the replies that you recieve have to say.

Michael.

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R Dupraz posted this 17 January 2013

You are welcome and thanks for your reply:

As an after thought I remembered to check the archives and found pretty lengthy discussions on the topic. One thing that was interesting to me, after reading these were the reasons that the posters gave for heat treating or not at all

However the reason that I thought of heat treating was absent from that discussion. And it is the possibility of using the method to shoot a heavier/longer bullet that would otherwise not be stabilized in a certain twist by making it harder. Therefore increasing the velocity in order to stabiize it. This is kind of interesting to me.

I too have a 25-06, a heavy barreled Rem. 40X single shot that once was one of my praire dog shooters. It has been unused for some time but now that you mention the 25, think at some point it would be interesting to see what that rifle would do with this 120 RCBS. Have never checked the twist but I'm betting it is also a 1-10.

I'm just at the point now where I need to return the mould. so I'm going to empty my lead pot today to get a few 120's untill I can find a mould of my own. Going to try to convince Norm to sell it to me as it turns out that the bullets from it fit the .257R perfectly.

RD

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Michael K posted this 17 January 2013

Early on years ago when I first heard/read about heat treating I thought more velocity for stability or “just because” were the reasons why. I have since come to realize folks HT for a variety of other reasons as well. The stability issue has been an issue with my 218 Bee using the 22-55-FN. Heat treating may be worth a try and it does cost less than new mould. The last time I looked, RCBS still offered the 25-120-SP. Looking forward to hearing how things go. Michael

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onondaga posted this 17 January 2013

http://www.castbulletassoc.org/view_user.php?id=7095>R Dupraz:

You came upon the exact reason ( sizing heat treated bullets) that I stopped experimenting with hardening of cast bullets altogether either by drop chilling or by oven heat treating and quenching.

I mix my alloy to the hardness I choose to match the job. all of my gas checked bullets are from a Lyman #2 clone. All of my plain base bullets are alloyed specifically to the hardness guidelines of Lee related to load pressure.

I take this hardness thing seriously about my bullets and check bullets of every batch with the Lee Hardness Test Kit at one hour after casting and at one week after casting My #2 alloy is BHN 15 at one week and BHN 14 at one hour very consistently.

Gary

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pat i. posted this 17 January 2013

Gary what problem did you run into sizing heat treated bullets?

RD size em now size em later it's up to you and eithr way works fine. The only difference sizing before or after hardening makes is if you wait until they're hardened up the diameter might be a few tenths bigger out of the die. If you're not using one already do yourself a favor and get a Lee Push Through Die to size the bullets and lube in a lube sizer using a .001 over H&I die.

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onondaga posted this 17 January 2013

Pat,

 The question of hardness changing from sizing bugged me. Also The whole heat treating cycle bugged me due to sensitivity to temperature changes dramatically affecting hardness even if bullets are hardened after sizing. There is an inherent inaccuracy of temp stability with drop chilling and also with oven heating cycle accuracy. After getting an alloy to the hardness I want without heat treatment and then just size/checking, the whole heat treat thing is avoided for me and has worked well for me. My hardness tests are much more consistently controlled with alloy content and no heat treatment. I believe this hardness consistency of the alloy alone limits a variable that effects my group size better than hardening does.

Gary

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R Dupraz posted this 17 January 2013

Pat:

So you are saying that the hardness of the quenched bullet is not effected by when it is sized?

A couple the guys around here use the push-up die method and I can understand the advantages. especially by not pushing on the nose as one normally would in a conventional sizer. This has crossed by mind but it looks like I would have to have Lee make me a custom one because I don't see a .257 listed.

One little detail, among others, that has cropped up is that the nose of the bullet from this mould is right at .251” which is a perfect fit. Except that when sizing in my Saeco, if not careful the pressure of the punch will expand the nose to .252+. In which case the bullet gets pushed back in the case when chambering.

This whole project is just getting started and if it looks like it's going to turn out, the pushup die is on the list.

Next stop is the 100 yd line if this weather holds out.

RD

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R Dupraz posted this 17 January 2013

Gary:

How much of a difference did you notice in group sizes between the quenched bullets and your unquenched alloy? How inconsistant were the quenched bullets?

Do you have a method of measureing pressure?

RD

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onondaga posted this 17 January 2013

Pat and RD,

 I did a lot of heat treating with COWW, both drop quenching and oven treating. I had extremes in both cases with the COWW running from BHN 16-22.

My alloy  only method with a Lyman #2 clone  has BHN 14.5- 15.5,  no matter what I do, I don't get extremes to BHN 22 with my Lyman #2 clone alloy as cast and at 1 week.

The groups resulting from the alloy only method have substantially less fliers. I only really trust 10 shot groups for a definitive accuracy evaluation. The typical hardened bullet groups had 1-4 fliers ruining many 1 inch groups at 50 yards in .500 S&W, .458 Win Mag and .375 H&H. The small calibers such as 7.62X39, 30-30 .308, 30-06  and .223 Rem  have been less afflicted with the flier problem from COWW hardening but group averages of the small calibers saw about 10% group size reduction with the #2 alloy only method. Nothing scientific, just my observations. This has been very convincing to me personally with my rifles....enough so to completely stop hardening bullets and depend on my alloy mix accuracy for hardness.

My last couple of batches of bullets for .500 S&W and .458 Win Mag have been a harder alloy of BHN 16-17 by adding additional Linotype to the mx and accuracy was not lost when I upped my velocity from 1600 to 1700 with a plain base 350 grain bullet Plus BPI  in the .500 S&W and the same weight GC bullet in .458 Win Mag.  I did this due to more frequent Bear sightings and sign in my hunt area convincing me to want a little more velocity with the rifles for Bear. I don't run very fast or shoot as fast anymore.

I have no pressure measuring stuff and rely on the formulas of Richard Lee for pressure calculations by sequential 1% load reductions with his formula from book values of load pressures in PSI . I believe the Lee method has merit and is very practical with plain base bullets to indicate an alloy hardness selection. Gas checked bullets have great leeway beyond the Lee projections..I wish I could put a number on that!!! I can tell you the relationship is not linear in my estimate and more likely elliptical in a bell curve with gas checked bullets.

That imaginary ellipse peak in bullet hardness with gas checked  bullets and load pressures is something I can not prove other than by dispersion in groups increasing at a brisk level at some point in pressure rise. This indicates that there is a high likelihood other factors are relevant too. I went there many times in 25-06 that I no longer shoot. Velocity has lost it's value to me as a result.

....and bear in mind that most of us are only melting scrap lead and pouring it into a hole!

Gary

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pat i. posted this 18 January 2013

Gary all I can base my opinions on are the results of 100 and 200 yds match shooting over the years. I'm probably one of the few if not the only guy that used and still do use heat treated or quenched WWs. I've been beaten by guys using lino or some other concoction of their own making and I've beaten guys that used lino or their own concoction. BUT I'd be willing to bet I would have been beaten by some of them if I was using Berger bullets and they were using cast. I've quenched a $%!&jouse full of bullets and if you were getting swings of 16 to 22 BNH with quenching I'd have to see what you were doing because I never had that happen. Maybe a swing of 1 or possibly 2 BNH but never 6. Obviously you were doing something wrong and I'd have to have more information to make an educated guess as to what. I'd have to sit down and watch someone with a pretty substantial sampling of bullets in a warehouse to prove to me that a couple of BNH made any difference on a target.

Alloying for hardness is perfectly fine if that's what a guy wants to do but must be costly. I can accomplish the same thing and more with plain old WWs.

RD yes I am saying the hardness of the bullet isn't effected by sizing. Bullets are hardened all the way through when heat treated and quenched so why would sizing it a couple of thousandths make the whole bullet soft?

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onondaga posted this 18 January 2013

Pat ,I can keep the swing lower than up to 22BHN with a reasonable accurate thermometer in the oven. The big swings were from oven treating with only relying on the oven thermostat .  In the 3 different kitchen ovens I have tried, the best one had a +-  20 degree swing cycle. That really stinks for heat treating because you really cannot heat soak with a swing like that and a thermometer will have you playing games trying to catch a particular peak or dip.

That is still another part of the reason I abandoned heat treating Pat. I don't have any odd games like that mixing alloy and results are much more predictable and easier for me to achieve.

Cost is not a factor so far for me. I still have several hundred pounds COWW, about 50 pounds Linotype and Range scrap is still free for me to collect. The Lino is only $1.47/ lb locally.and is my only real cost . 7:3 ratio range scrap:Lino gets me BHN 15 and,   13:3  COWW:Lino gets me BHN 15,  and 8:3 COWW:Lino gets me BHN 17 These are the alloys I use except straight range scrap for buckshot, rifled slugs and ML bullets/round balls. It is actually all pretty cheap.

Gary

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pat i. posted this 18 January 2013

I've never heat treated a bullet in a regular oven for the simple reason that I eat stuff that comes out of them and cooking lead and food in the same oven never sounded very appetizing to me. I bought a toaster oven years ago and have used it ever since. A toaster oven and a decent oven thermometer is all you need to get consistent results. With quenched from the mould bullets I might get a swing of a BNH point but if there is any difference on the target I don't see it. A little wind will make a heck of a lot more difference to group size than a BNH point or two.

With WWs with a little tin thrown in for good measure I get around 10 BNH dropped from the mould. 20 BHN quenched from the mould. And 35 BNH heat treated for an hour at 450 degrees. Now the beauty part is that if I had the time, inclination, and energy I could also get anything in between.

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madsenshooter posted this 21 January 2013

Dupraz, try a much slower powder with your harder bullets, maybe even one thought to be too slow for the combination. The slower pressure rise might give you enough velocity to overcome the instabilty. Even as slow as the the 50BMG powders like WC860. A caseful of it will net you around 2300fps with that bullet weight. Burns dirty, but gets the job done.

Most gas ovens have too much temperature swing for heat treating bullets. Nothing like finding all the bullets you've checked and sized have become puddles in the oven.

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R Dupraz posted this 21 January 2013

madsenshooter:

I have seen where others have talked about this several times. However, for now I am going to see if this RCBS 120 will shoot in the Roberts with 4227.This powder has given me fine results in an Israelie .7.62 mm, a 32-40 and my 38-55. The last two, when breach seated. And an M1 Garand. All with cast. What I'm after is accuracy out to 200 with The 722.

I posted the 100 yd targets few days ago under a different thread. These bullets were water dropped from the mould. and the groups were encouraging. So the next session will be to see if they can be duplicated at 100. If that happens, I'll give some ten shot groups a go. Then on to 200.So far, so good as they say.

At some point, I would like to try a slower powder but I want to see where this goes first. The temp. has dropped out here in God's country so looks like it's going to be a while now.

RD

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tturner53 posted this 21 January 2013

Good shooting. It's always nice to see what someone else is doing and especially something besides the standard .30s.

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R Dupraz posted this 21 January 2013

Thanks,

Have had this old Rem for quite a while and it has always been a good shooter with jacketed. That's why it's still here. And, have never seen a .25 appear on any tech sheet let alone a .257R. Kind of different. So thought it would be fun to see if it will shoot cast. Have never been one to march to the music anyway.

One problem I know I'm going to have is seeing those .25 cal holes at 200 in the black. I's going to be iffy I think in the white, even with a 27X scope. Maybe I can get someone to stand down there with a radio or something. NOT!!!!

RD

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pat i. posted this 22 January 2013

"Nothing like finding all the bullets you've checked and sized have become puddles in the oven."

Don't put the check on until after they're heat treated. Melts around the check otherwise.

Have never been one to march to the music anyway.

I like that. That's why I built the 6.5 PPC I used to shoot and the 30x47 I was using not long ago along with a lot of other goofy stuff. It's also why I'm playing around with a PB in the 30-06 now. Might not always work out but the fun is in the trying.

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Ken Campbell Iowa posted this 22 January 2013

don't expect much improvement in stability from an increase in velocity.

better to cut off the nose of the bullet a bit .... but of course now you could lose your slick form  .. heh heh, dang compromises. 

of course when shorting ( in a lathe...or ” bumper  gadget  “  )  you could leave the nose sharper ... but that means moving the center of pressure forward ...ooops ... another compromise .

wow !  at least i have a complete understanding of wimmin critters ...

ken

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R Dupraz posted this 22 January 2013

D**n Ken! Just when things were going along so good. What are you trying to do? Blow my “KISS” principle all to .... with all this tec..TEchnicale stuff.

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billglaze posted this 15 March 2013

I have had little trouble spotting 6mm holes at 200 yds with the riflescope, (24x Unertl) or my regular 20x spotting scope. Admittedly, the mirage wasn't running as it used to when I lived in Las Vegas, but the target being used is the official orange CBA target, which is a big help over the usual black/white targets. As far as sizing and then hardening, I was doubtful about sizing after tempering, until I spoke to a real cast-bullet guru, who advised me to “go ahead, and temper then size.” Seems to work just fine. I got to thinking about it, and, just like watching the baseball getting larger and larger, then it hit me: The tempering isn't like case-hardening, it goes clear through the metal. I've checked before and after with an LBT hardness tester, and found that the driving bands hadn't softened an appreciable amount. But, worthy of consideration is that the newer sizing dies are more like swaging, in that they have a tapered leade, and don't shave the bullet the way the old dies did. Accuracy: While by no means is it record-setting, it doesn't seem to be hurt by the temper/seat process. So far, at least. I caution: the above is my experience. YMMV.

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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