cast 230gr bullets breaking in toaster oven

[NATJAC]

Hi,
This is my first post, i just signed up. I am just getting into casting and have been following your forum for a few weeks now.. I really thank all of you for your knowledge and experience!!
I have encountered a problem, I recently casted up a couple hundred bullets (lee 230 gr for 300 blackout) and I did the powder coating thing.. but when i put them in the oven i drilled holes in a piece of metal and tried to stand the boolits up-nose down in the holes. After cooking at 400 degrees for 15-20 minutes, i pulled them out and i noticed that some of the tips of the bullets actually broke off, and some were bent. At the break off point the bullets' interior looked "frosted" and not melted (see attached picture), what did i do wrong??
NOTE: While casting, my pot did get over 900 degrees and some of those boolits may did come from that temp.. but with the boolits looking good i decided to keep them and not recycle.. After I cast the boolits i did notice frosting.

[dahermit]

What kind of a casting pot do you have that would take the alloy to 900 degrees? How did you measure that temperature? Have you put an oven thermometer inside you oven and checked that actual temperature that is achieved when it is set to 400 degrees? What bullet alloy are you using?

Just off hand, I would say lower the temperature in your pot so that it is closer to just over the melting temperature of your alloy, check the oven temperature. Also, it would appears that from the crystalline structure, there is too much antimony in your alloy try diluting it with more pure lead.

On the other hand, your powder coating job looks really good.

[runfiverun]

900 degrees holy cow, I woulda flipped out.
that would have over heated the mold and the alloy both the sprue never would have hardened.
throw them back and get that pot temp down to about 725 where it belongs, that's plenty warm enough to pour frosty boolits.
your mold temp should be monitored as well for good consistent boolits in fact the mold temp is the critical temperature here.

over 900 man. you changed the crystalline structure of the alloy at that point.

[LAGS]

900 degrees ?
I hope you were wearing a Gas Mask.
That is up to the point where Lead Boils and becomes really Toxic.

[NATJAC]

RE: dahermit: I was using a lee 20lb pot. and i did use a thermometer. I put it on high heat to melt the ingots and once they melted I changed the setting to #7, the temp was around 650 so i started to run a few casts to warm up the mold... after a few casts the boolits started to come out really good so i thought i was good to go... but after about 20 or so casts i checked the temp again and it was over 900! I gradually turned the dial down (while continuing to flux) until I got to #2!! and the temp finally went down to ~700 so i made a few more casts and then called it a night.

The lead is "isolead". I have no clue on how to determine the tin/antimony in it, i just used this for a reference: http://www.fellingfamily.net/isolead/

I didn't have a thermo for the oven... i guess i should do that next time!

[NATJAC]

RE: LAGS: no kidding! i was using a shade tree mechanic ventilation system i put together... worked really good! (windows/fans/etc)

[NATJAC]

900 degrees holy cow, I woulda flipped out.
that would have over heated the mold and the alloy both the sprue never would have hardened.
throw them back and get that pot temp down to about 725 where it belongs, that's plenty warm enough to pour frosty boolits.
your mold temp should be monitored as well for good consistent boolits in fact the mold temp is the critical temperature here.

over 900 man. you changed the crystalline structure of the alloy at that point.

I thought my thermometer was broken... i was freaking! especially casting for the 1st time!

[Smoke4320]

put them all back in the pot.. remelt at no more than 750 and add 1-2% tin ..
Make sure your Powder coating oven is at an actual 400 degrees.. preheat oven then add bullets for 15 minutes and all should be good

[NATJAC]

put them all back in the pot.. remelt at no more than 750 and add 1-2% tin ..
Make sure your Powder coating oven is at an actual 400 degrees.. preheat oven then add bullets for 15 minutes and all should be good

Thanks Smoke4320! btw, what's the easiest/cheapest way to add tin?

[Taylor]

Pewter,check your local flea markets.

[dahermit]

The lead is "isolead".

Isolead as in "Medical Isotope Shielding". Here is some info on those types of alloys. http://fellingfamily.net/isolead/

[leeggen]

We all have screwed up once or twice some of us more but who cares it is in the learning curve to casting.
Welcome to the sight, and read, read and read.
CD

[NATJAC]

Thanks all!

[Smoke4320]

For tin you can also visit the swap & sell section.
One vendor is imashooter. He sells pewter ingots in small coins . easy to add to lead.

I get hi speed billet for the added copper as i do mostly rifle bullets and like speed.
We will be waiting for good bullet pics

[Hickok]

If you can't find any tin/pewter locally, go to the hardware store, look for tin solder, read the label, and get a roll with the highest tin %. Pricey, but it will work.

[ryokox3]

I have cast with that same mould and found it is very easy to bend the tips after casting. It just did not cool fast enough and the shape helped it bend when I dropped them onto a cotton towel on my workbench. Going forward water quenching with that mould for me.

[ffries61]

900 degrees ?
I hope you were wearing a Gas Mask.
That is up to the point where Lead Boils and becomes really Toxic.

Not really, boiling point of lead is much higher than that.

[11B-101ABN]

When I get broken boolits like your photo, it is usually because I dumped them from the mold before they were sufficiently cool. How long did it take for the sprue to cool with your "hot" boolits? This is not an exact science, and probably no two people use the exact same alloy. If you let the alloy level in your pot get too low it will cause the temp to rise. I keep the level in my casting pot within an inch of the top by returning sprues back into pot immediately, also have toaster oven set to 375 preheating my ingots to keep level up. You might check into a PID controller to keep temp under control. Lastly, put your location in your name box, maybe someone that is located close to you will offer hands on help.

[rototerrier]

One thing I'd like to throw out there is to make sure you have the thermometer calibrated. I have a nice TelTru that I cast with for about a year before realizing it was off by 100 degrees. Of course, I didn't much care what the temperature was as long as I was getting consistent and desirable casting results from the alloy. I typically shot for around 780. After calibrating the thing, turns out I was casting at 680. It all really became evident when I built a PID and set the PID for 650 just to start and my thermometer was telling me I was at 750.

Anyway, could be possible that your thermometer is a little off and you didn't really go over 900 since that's a very high overshoot. Just want to throw that out there as something to look into.

[fredj338]

Not sure a full Lee pot will get to 900deg, maybe. I would also verify the oven temp, cook less time, cool 100% before removing the bullets from the plate. I've been casting on & off for 35yrs, never "broken" a bullet.