Can anyone explain this?

[JWFilips]

Over the past few years I have picked a few hundred pounds of lead & bullets off our public range. Just walking the berms each trip to the range and picking up what is laying on top. When I get home I wash it clean & store it away in buckets. Well this late fall I decided it was time to smelt it all. On our range 50% of the pistol shooters use Commercial cast bullets ( hard cast BHN18) on our rifle range 25 % of the shooters use a lead alloy enriched with linotype. So before the smelting; my wife.(..the angel that she is) & I sat down and hand sorted all the buckets separating the jacketed projectiles from the cast bullets. It took two days!

My first smelt was all the cast bullets & I ended up with 101 lbs of ingots
The next smelt was all the jacketed & I ended up with about 130 lb of ingots. Now after a month & a half I tested the hardness of both. The Jacketed ingots are at approx 10 BHN

But when I checked all the cast bullet ingots they are only at BHN 11/12!
I was surprised by this because the commercial alloy is normally hard cast BHN18
I thought the cast batch would be much harder then it is!

Now I almost regret all the extra work to separate it all!

 

[Rick]

First, I'm not a fan of BHN testing ingots. The reason being that what will determine the final BHN of a lead antimony alloy is it's rate of cooling. An ingot is MUCH larger than a bullet and the ingot will cool much slower than a bullet, considerably more so air cooled.

 

[Ian]

Rick nailed it, you can't tell anything by testing ingots because they air-quench at an abnormally slow rate. If the alloy contains a good bit of antimony it can be tempered quite soft by a slow cooldown. You can do the same thing to bullets in an oven by heating to the tempering/hardening temperature and drawing down to room temperature over the course of an hour or two.

A tip to counter this is to grab whatever bullet mould is handy when smelting (I prefer a wadcutter or something with a WFN for easy testing on the nose) and cast a dozen or so air cooled and a few more quenched into a coffee can of water and use those samples for getting the BHN of the batch. Also, testing both AC and WC bullets for hardness immediately after being cast and once a day for two weeks can tell you a LOT about how much antimony and tin your mix has in it.

 

[freebullet]

Interesting information presented here. Thank you Rick & Ian for the explanations. The difference in final results with different alloys and how to manipulate what they can be is an intriguing study.

I don't even wash range scrap. Just Flux & scrape the pot 3 times and all the junk floats on top for skimming. I melt it down 150 lbs at a time. I skim and drain the jackets before flux/scrape.

 

[Ian]

If you want to know more, google up "precipitation hardening". That's what happens to antimony when alloyed at a few percent with lead.

 

[williamwaco]

What Rick said.

Bullets cast from an ingot will never test the same BNH.

That said, every ingot I have ever smelted from range scrap tested between 8 and 10 whether they were jacketed or not.

One batch of all jacketed ingots tested 9.6. ( I have not cast any bullets from that batch. )

 

[KHornet]

For what ever it is worth. I water drop most every thing I cast, mostly as a matter of convenience. At the end of the session I cast about a half of one of the small ingots in a lee mold, making it about a quarter of an inch thick and then I water drop it as well. Have found that the thin ingot tests very close if not exact to the blts I cast and water drop. They age to the same BHN as well. I would agree that a large ingot cast different from the bullets you are casting will be appreciably different.

 

[JWFilips]

Wow! you guys still teach me things everyday! That explains so much. About 4 years ago I smelted a small batch of range lead (Jacked and cast combined ) And it tested the same as my new separated batches.....Now I understand why! Thank You! Today's a great day I learned something akin to COWW ( for my .30 & 8 mm & 35 cal light load rifles and then hardened I can use it for my faster .223 & .243 rifles (?)

 

[Texas Hillbilly]

Yep New trick for this old dog too, I had one old man tell me he doesn't water drop anymore,but uses anti freeze in place of water to make his small caliber bullets harder,I haven't tried it yet,but I will some day??
Any body tried this or even heard of it??

 

[Brad]

I know some people use ice water. I just use tepid tap water for quenching, it gives the hardness I'm looking for.
Best thing to do, in my opinion, is try a few different things and test hardness over a period of a week or so. See what happens each day to hardness. See which shoot best in your guns with certain loads.
I did the testing and now feel pretty confident that I can adjust my bullet hardness via heat treating to get pretty close to a desired hardness with my alloy.

 

[John]

My tap water is about 40 F from the well, warms up to 41 F in the summer. I get different results than when I lived 150 miles west with 55F water.

 

[Rick]

Experimenting with water temp is one of my round-to-it things. Back years ago when I was using a conventional gas fired cook oven to heat treat several different attempts with ice water and cool tap water resulted in a bit higher BHN a bit quicker with the ice water. Once I went to using an electric convection oven the difference between ice water and tap water temps disappeared. Heat treating a batch in the convection and I had no ice I got the same results as with the convection oven and ice water. I then did several batches alternating between ice water and tap water with the convection oven and there was no difference in final BHN or the time to get there. I found that rather perplexing and intended to test further doing the same tests over again with the conventional oven but never did get round-to-it. Ever since then I've used only the convection oven and cool tap water. Is there a difference using colder water? I don't know, it sure seemed so with the conventional oven but it would take several more tests to get an answer that I would feel confident saying one way or the other.

 

[JWFilips]

Just So You all know I' m still here...taking it all in! Thank you

 

[KHornet]

Would be interested as well if any body tests the anti freeze drop test. Am satisfied with cold water, but am always interested in a new mouse trap type thing.

 

[Rick]

I doubt anti freeze at the same temp as water would draw heat out of bullets any faster than water. If using ice water the coolest that's practical is water temp in the 30's. It could make for some interesting tests if the anti freeze was chilled to about zero or below in the freezer and see if those temps would make a significant difference in final BHN. Sounds logical that anti freeze that cold would draw the heat out pretty quickly.

That brings up the question of "just how hard do you need your bullets"? I can get clip-on WW alloy easily to 30 BHN with water and that's much harder than any need of mine. Then of course there is the curiosity of the "what if" factor?

 

[RBHarter]

I read an article a number of yr ago in a 4 wheeling magazine, stay with me. Straight water actually had better cooling than glycol based antifreeze the only exception was at 25% or less and then it was only about 5 degrees. Glycol is used to both raise and lower the boiling temperature and the freezing temperature of water 50/50 is as good as it gets . It is used for short drop shot makers but I suspect that the fluid density has as much to do with the effects as cooling capacity. With 10% you can get the water down to about 10 degrees if I remember the chart right . However I have maintained ice at 19 degrees with nothing more than table salt .
The trouble is that anything that we drop them into will have some effect on the bullet or lube . If you have room in your freezer isopropyl alcohol, Walmart shelf grade, will buffer the freeze point , at 50% it is firm slush at about 5 degrees and should have a near negligible impact on lube without crusting like salt. That would get you a 20 degree head start at least . I don't have data for a stronger mix memorized but at some point it will become flammable probably around 70%. That I would guess would get you to sub 0 . Don't let your dog get into it, I guess you could use Vodka if you're worried about a dog or cat.

 

[freebullet]

Antifreeze holds heat.

Add more antifreeze to a cars coolant mix will make it run warmer. We used to do that on purpose with our van powered machines. We ran straight antifreeze to boost the entire system temperature to in turn raise the temp of our output water. The heat exchangers provided enough cooling effect to not overheat the vans.

The really interesting test would be to use sub 0 chilled antifreeze vs. Plain cool tap water. Would cooling the boolits faster by 50 or more degrees work the same as raising the temp of the oven. Don't have a hardness tester to find out yet myself.

 

[Brad]

If I find a box of extra time I may just look into this. Even ice water vs 100 degree water would be a good test.
If the temp difference is what matters the we should see some difference.

 

[Bret4207]

All of which brings me back to wondering why the drive to create HARDCAST?!! If there's a specific, quantifiable reason, fine. But I have yet to personally see where a 20-25Bhn bullet performs better in my uses than those in the 12-18 range up to the 2K range in rifle or 1.2K range n handguns. I suppose if someone has a load/gun combination so temperamental that only one alloy at one Bhn works, it's a good reason. But age softening is going to require shooting the loads up within a specific period of time, barometric pressure and ambient temperature might be factors...you get the idea.

No disrespect to anyone intended, just wondering what the drive is.

 

[quicksylver]

+1 on Bret's
Add bullet fit, lube and seating depth as well as Ben's groups w/
COWW +2% Tin, outside of having fun, what is the need?
Just curious.
I do recognize that many at the CBA site use straight Lino.
Velocity increase?
Or getting the 22 cals to shoot?