Broken Boolit... Any ideas?

[queeg730]

I cast a lot of 158 gn LSWC, and powder coated them.

• The casting temperature (PID controlled), was 360 Celcius, (680 Fahr).
• The coating temperature (PID controlled), was 145 Celcius, (293 Fahr) ---- I realise that most folks say about 205 Celcius, (400 degrees Fahr), but I got the number from an experienced coater, and thought I would go with it... this may be a big no-no!
• The time in the oven was 15 minutes
• I did 2 coats of powder

After the last coat, I quenched them in water, and when I removed them from the water, I found this one in the pics.
It had simply broken in half, and the exposed parts look very crystalised. There is only this ONE in the batch which did this, but of course, now I dont know what the state of all the others would be.

The first pic is simply the two halves sitting on top of each other.
Any ideas on this, and more importantly, can I trust the others to shoot minor loads in both 38 Spl, and 357 Mag?


Grateful for any thoughts!
Mike

[OS OK]

I would take a look at the hardness of that cast and several others in that batch of Pb, try to determine if this is a 'one off' rather than reflective of the entire melt. That's strange, I don't recognize that grain, it looks more like cast steel than pure antimony. Thinking you got a gob of separated Pb, Sn & Sb through the valve or if you dip and pour, you got Sb off the top of the melt?

We'll both learn from this, I've never experienced this before.

[M-Tecs]

My guess is its a result of the bullet still being too hot when you opened the mold. Reduce the alloy temp or let the bullet stay in the mold a little longer. The coarse crystalline is common with harder alloys when you crack the bullet when the alloy is still solidifying.

[queeg730]

Thanks OS...
I haven't experienced this either!

I cut one in half using a hacksaw... I expected that it would look OK, just because of the fact that I used a hacksaw.. and it did.
I haven't got a hardness tester, but using the pencil test, the first one to scratch the exposed lead was a 'H', so I thinking somewhere around 20-22 BIN (which is probably harder than I expected).
I tried another boolit in the vice, and hammered the nose to see if I could break it... no go.. it just bent a little, so I used it as a smash test dummy... smashed down OK, with no PC flaking off.

Your theory is good... I just hope that not too many are like this first broken one.

What do you think about shooting these in minor loads (38 Spl & 357 Mag)?

[queeg730]

My guess is its a result of the bullet still being too hot when you opened the mold. Reduce the alloy temp of let the bullet stay in the mold a little longer.

Makes a lot of sense...
Thanks M-Tecs

[358429]

Opening the mold too early

[243winxb]

Results of pouring a cold alloy into a very hot mold.

Test- bring the pot temperature up slowly so the alloy just melts. Surface should look like oat meal. Lumpy. Dont flux or disturb.

With sprue plate open, fill cavities . Watch as mold heats up. I would guess the molecules will not bond together.

[Tar Heel]

What is the alloy? I wonder if you got zinc in there.

[243winxb]

" 20-22 BIN" Your "BHN" tells me there is a high % of antimony in your alloy.

"casting temperature (PID controlled), was 360 Celcius, (680 Fahr)." Temperature to low/cold . Brittle Bullets

[Tripplebeards]

I’ve had it happen when I use to quench. The boolit was WAY to hot when it was quenched and came apart. Think of volcano lava hitting the ocean.

Had it happen many, many times opening my mold to soon when casting HPs really hot at 8.5 on my lee 4/20 pot.

[dverna]

I have not cast as many as most here, but have never seen anything like that. But I do no use "mystery alloy" made from whatever I can scrounge up.

I find it interesting that only the OP and 358428 have pictures of it and they both powder coat.....any connection?

I do not buy the alloy too cold reason IF you have good fillout. I have never had good fillout with cold alloy.

Strange>>>>

[Larry Gibson]

" 20-22 BIN" Your "BHN" tells me there is a high % of antimony in your alloy.

"casting temperature (PID controlled), was 360 Celcius, (680 Fahr)." Temperature to low/cold . Brittle Bullets

That is the problem. Too much antimony and too little tin. I suggest you add 40% pure lead and then add 2-3% tin to that alloy. You will end up with a very good alloy for .357 loads.

[queeg730]

Thanks again to all those replies... a wealth of great information!

I think the consensus is that the mold was opened too early, and the crystalized metal on the harder alloy makes sense.
And quenching immediately after the oven is another good one... In future I will let them cool a little.

I never had this issue before, but that is probably because my alloy was softer, and cooler.

I have learned a great lesson here, thanks only to you folks!
My casting knowledge has improved by leaps and bounds because of this post, and I can't thank you all enough.

Mike

[Dusty Bannister]

Was the BHN reading 20-22 after quenching from powder coating and baking? And how much time passed before taking the reading. Is it possible that the castings are being dropped from several inches onto a poorly padded surface? That might start a fracture on a hot casting that has not solidified yet.

[mdi]

I'd go with too hard alloy, too much antimony and water quenching. First I'd cut the alloy with equal parts pure then air cool and PC. This should be around 14-15 BHN. Give that a try and I bet you'll get better bullets (Don't know about too quick mold opening or mold temp. The crystalization tells me the problem is from a water dropped too hard alloy)...

[OS OK]

Thanks OS...
I haven't experienced this either!

I cut one in half using a hacksaw... I expected that it would look OK, just because of the fact that I used a hacksaw.. and it did.
I haven't got a hardness tester, but using the pencil test, the first one to scratch the exposed lead was a 'H', so I thinking somewhere around 20-22 BIN (which is probably harder than I expected).
I tried another boolit in the vice, and hammered the nose to see if I could break it... no go.. it just bent a little, so I used it as a smash test dummy... smashed down OK, with no PC flaking off.

Your theory is good... I just hope that not too many are like this first broken one.

What do you think about shooting these in minor loads (38 Spl & 357 Mag)?

I would be hesitant to shoot them in a semi-automatic, I have heard of folks breaking them like this from them rolling off the bench and hitting the floor (way too hard of lead for general casting)...I shutter to think of one breaking as it goes into battery in my 1911? Not sure what the outcome would be when I set it off?

In casting, wait till the Pb on the sprue plate solidifies, then add 2 or 3 seconds to that and the cast should be cooled enough to make a drop...I use a padded piece of 1/4" plywood to drop onto...the pad is just a 'clean' folded cotton rag...



Then too, I drop from only a couple inches & they land softly and roll into the pan...they tend to dent against each other much less this way also.
I generally cast between 700ºƒ & 725ºƒ...all depending on the ambient temperature in the garage. Cooler air temps. will alow my spout to freeze up and I have to use a torch to un-freeze it & then I'll crank the PID 10 degrees hotter until the spout-freezing stops.

I preheat the moulds on a hot-plate to 300ºƒ ~ 350ºƒ and I get good casts much sooner starting out the session. If I want to take a break or I have to re-fill the pot, I set a filled mould back on the hot-plate & everything is 'good-to-go' just as soon as the pot is ready again.

You may find this an outstanding reference...



http://www.lasc.us/Fryxell_Book_Contents.htm

[queeg730]

Folks, again thanks!
I have learned a lot from this post.

1. The mold was probably opened too quickly
2. Immediately after coming out of the oven, I drop in water from a height of about 2 feet! (yes, 2 feet), so I should give the boolits a little time to cool off, and drop from inches high rather than feet
3. Furthermore, there is no padding in the water bucket.
4. Also, the pre-cast ingots are about 12-14 BHN, it seems to be the water quenching which pushes it up, so I may not even water quench at all, considering the boolit is powder coated.

Yes... lots of great lessons learned!!
Mike

[Shanghai Jack]

Zinc poisoning?

[RKJ]

I use a padded piece of 1/4" plywood to drop onto...the pad is just a 'clean' folded cotton rag...

OS OK I had never thought of using plywood and cloth like that before. Thank you for the idea. Queeg730, sorry for the hijack, I've learned from the discussion too. I've not had an issue with PC but I don't water cool and I tend to wait quite a while before dropping the bullets. Hope that didn't sound condescending, it wasn't meant to be.

[queeg730]

RKJ.... no problem re the hijack, and I didn't take anything as condescending...
Every single point that everyone here has made has been just excellent! We are all learning, all the time, no matter how long we have been doing this!

Mike