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View Full Version : Temperature too high or not enough Tin?



2ridgebacks
04-21-2014, 01:13 PM
We were running our BC Mark X last night for a couple of hours. We have not had a chance to melt down our range scrap or homogenize our isotope lead yet and the stuff I have processed wasn't readily available. The pot was about half (50lbs) full with processed range scrap (composed almost entirely of swaged 45's and 22lr) and we added what was likely pure lead from isotope containers to it to bring it to full. We started warming the molds when the IR gun indicated around 750 and had them as high as 235 degrees. We had an issue with sprue plate alignment that was causing a badly deformed base that we had attributed to cold molds and low lead temp. But, as the mold temps and lead temps continued to rise, it didn't clear up. After fixing that small issue, the molds were very hot, 235, and we had the melt way too hot, like around 1000. All in the name of trying to get good fill out. The molds were casting well, and we starting saving all of the bullets that were dropping. The pot was cooling and then we added additional, likely pure, lead. When the temp got down around 850 as indicated by the IR gun, the bases started rounding off again. Back up to around 950 and they were all keepers. There also was no frosting. The bullet weight went from around 203.3 to about 208 as well. Diameter was consistent with the previous batch.

Have we lowered the Tin content to the point that we are having to use very high heat to get fillout? If that is the case, will it hurt anything? What is a suitable mold temp? Would heat this high contribute to sprues sticking? Bullets sticking in the mold? I've been reading and searching, but I'm look for something conclusive.
Thanks in advance.

cdngunner
04-21-2014, 01:18 PM
If you hit 1000 you likely burned off some of the tin . you probably did not have enough tin in the first place. Tin is what helps with fill out

With what I have read you should be around 650-700

Some IR guns can not be trusted as the beam reflects on shiny surfaces. Drop in a dark hunk of steal and read temp off of that

R.M.
04-21-2014, 01:29 PM
I get rounded bases when the sprue is too small, or the plate not hot enough.

2ridgebacks
04-21-2014, 04:46 PM
I agree on the IR accuracy. You do have to overcome the difference in emissivity of the shiny surface. I took the reading off of a pile of crud, the side of the pot, and the needle for the spout. It was a learning experience for sure. Now I need to figure out what it is that I learned.

cdngunner
04-21-2014, 07:50 PM
IIRC lead over 1000 degrees will give off poisonous gasses...

Maybe someone can chime in.