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Some help with heat treating  Rate Topic 
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 Posted: Fri Aug 16th, 2013 04:39 pm
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longcruise
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First, for clarification, let me explain the "why" of my question.

In a few weeks I'll be headed north to AK for a moose hunt.  Firearm will be an '85 winchester replica in 45-70.  Bullet is settling down to being a 405 grain with a fairly large meplat (Lee 90374) mith a muzzle velocity of about 1400 fps.  Casting will be with wheel weights.

So, now, I'm not new to heat treating wheel weight bullets, but in the past it has been a matter of max heat and then dump in cold water.  Makes a very very hard bullet.  Maybe too hard for my application.  My goal is to reduce expansion a bit so as to get good penetration without fracturing the bullet.  A small amount of expansion would be a good thing but too much might result in less penetration than desired.

Can anybody give me any ideas on an oven temp to use to get these bullets to somewhere around 15 or 16 BHN??  Also, how long do they need to "rest" in order to settle after dunking?

I don't have a hardness tester and not enough time to acquire one and learn to use it.  I know, I shoulda been all over this long before now.

Any help appreciated.



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 Posted: Fri Aug 16th, 2013 04:55 pm
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Duane Mellenbruch
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Heat treat a small batch as usual.  Remove from oven and wait 10 seconds before quenching.  Do another small batch.  Remove from oven and wait 20 seconds before quenching.  Do another small batch.  Remove from oven and wait 30 seconds before quenching. 

This will give you four known hardness bullets to try and probably will be ready to test in only a few days.  That would be your known hardness as heat treated, and then three with a delay while heat is lost before quenching.   Personally, I would retest for performance after a week or two as well.  If you can not decide which is better between two bullet batches, split the difference and do another small batch. 

That is the best guess I can give you since you do not have anything to test for hardness.  I hope someone has a better method, but you will still have to test some for performance anyway.  Good luck.

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 Posted: Fri Aug 16th, 2013 07:23 pm
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LBD
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1400 fps is not going to create very much expansion with air cooled clip-on wheel metal. I would test the air cooled metal after about 1 week in water jugs.  Your casting conditions are going to influence how hard your air cooled COWW will become.  Given that you are using Lee 90374 and air cooled COWW without specifying your alloy and mold temp (the latter of which is controlled by pouring rate) your bullets may end up BHN 13 or more in a month (there is/was no nation-wide standard for Pb based WW metal).

I would use this mold and push the velocity a bit more (1550-1650 fps) to get a strike velocity in the 1300 fps neighborhood:

http://www.midwayusa.com/product/632708/rcbs-1-cavity-bullet-mold-45-405-fn-45-caliber-458-diameter-405-grain-flat-nose-gas-check

I think your results will be more decisive and well worth the effort given the hunt you are planning.

LBD

P.S. The gas checks are also currently available at Midway.

Last edited on Fri Aug 16th, 2013 07:33 pm by LBD

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 Posted: Fri Aug 16th, 2013 10:55 pm
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hunterspistol
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Only by softening the alloy with pure would you be able to control the hardness of water quench unless, of course you vary the time as suggested. That would make for an experiment, if you have the time.

I've tried some wheelweight hollowpoints that didn't expand, now I prefer flatnose bullets. I could pour hollowpoints from pure/ww but haven't tried to see what ratio would expand. Even air-cooled wheelweights wouldn't expand much from a 9mm semi-auto. You could try them completely unquenched, I just don't know if they'd make it through the bore with good results.

    For my experiment in hardening, I found the oven needed to be 405-410 degrees.  Any hotter and the bullets got little shiny spots from the heat. 

Last edited on Fri Aug 16th, 2013 10:58 pm by hunterspistol



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 Posted: Sat Aug 17th, 2013 03:13 pm
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jhalcott
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I think those air cooled WW's should work fine! I MIGHT boost the velocity a bit IF I could stand the added recoil, and accuracy didn't suffer! I have used plain old ACWW alloy up to about 2000 fps with out a problem. Some stacks of wet newspapers or telephone books will give some idea of the penetration/expansion you can expect. Shoot the bales at the distances you expect to plug the Moose.

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 Posted: Sat Aug 17th, 2013 08:02 pm
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LBD
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jhalcott wrote: ...I MIGHT boost the velocity a bit IF I could stand the added recoil, and accuracy didn't suffer!
Sans the recoil part of the equation... that's precisely why I suggested the gaschecked RCBS version.

LBD

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 Posted: Sun Aug 18th, 2013 05:49 pm
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longcruise
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Well, I'm going to stick with my 1400 fps with untreated castings. Not concerned about recoil for me since my rifle is faily heavy and I'm not recoil sensitive to boot. My partner will be shooting a rather light (IMO) Rossi Rio Grande in 45-70 so he might have some recoil issues. When I get back I'll report on results. Hopefuly terminal results!



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