beltfed,  I will admit I have not spent much time researching alloys or antimony. My experience was mixing LR bullets 50/50 wheel weights and lead. When I was getting ready to go to DCRA BP match at Ottawa in 1995, all of a sudden I couldn't get a decent bullet out of my mold! 

That was about the time they started having stick on wheel weights here.  They had antimony in them and there were a few in the batch I mixed for Ottawa alloy. It took me a while to figure it out and get the mold cleaned.  I can't remember if I pitched the pot and dipper or if I finally got them uncontaminated too. 

I have no idea how much antimony (correction: it was ZINC contamination) was in those wheel weights, but I avoided them like the plague after that. 

oldman46 wrote on Mar 15^th, 2020 at 11:09pm:


I think you will find the gun will not read the shiny liquid lead temp. very well. I have one for other reasons but it does not work on my lead pot.

Hi Everyone! Thank you for the comments. 

On examining my mould I think I may be seeing something in the corners of some of the the lube-grooves. Not absolutely sure but it is worth trying a cleaning session. I will try the acetone soak and brush these areas with a brass-bristled brush. I'm afraid to use a regular tooth brush as the acetone may melt the bristles. I'm afraid also to boil the mould as water may become trapped in some areas and cause rusting over time.

I have now reamed out the pour-hole in my ladle to try and increase the flow. Its now about 0.190 dia. I did have one pour where I certainly did not have good flow and the bullet was not filled out at the base.

I do not believe I am casting at too low a temp. I use a Lyman thermometer which I confirmed its temp with a digital meter. I will recheck this. I hope I do not have an antimony contamination issue. Will keep my fingers crossed.

I think I have a good casting technique where I dip the ladle down into the melt and stir it a bit and when lifting it out I pour out a small amount of lead and then immediately join it to the sprue hole. I then turn both the mold and ladle to the up position. I leave the two connected for a few seconds and then allow lead to form a puddle over the sprue hole for lead to be sucked into the mold as it cools. I also wait a few seconds for the lead to further cool down before cutting the sprue. My bases are always filled out and sharp-edged. I do get good-casted bullets from a PJ mould of 429 gr, at the same temperature and same thermometer, but this is a different casting furnace and different alloy. So, I think my technique, at least, is good. 

It may be a while before I cast more 410 gr bullets. I've already filled up all of my styro-foam bullet trays as I also recently casted ~1,000 429 gr bullets of 16/1 alloy.

Thanks again for the comments!



 

I have a Barnett .32 mold that doesn't fill out reliably on one side. the second band can be noticeably rounded. If you cast left handed like CW said you will see the problem switches sides.  If you cast at a little higher temp you will see the problem diminish. I bet if your lead/tin alloy gets to 850 F. the problem will largely go away. According to "How to cast Bullets" by Ideal "Sometimes a bullet when cast will show grooves clean and sharply formed on one side while the other side will not,this may be changed by tipping the mold from left to right or pouring it right or left handed". "The side of the mold receiving the flood of metal will receive the full impression. The mold may be fitted to closely and the trouble is trapped air."  "To avoid this turn the mould and dipper up slowly." "Keep  the dipper connected for an instant so the shrinking bullet can draw metal from the dipper."

hepburnman wrote on Mar 24^th, 2020 at 11:55am:



I run mine with a PID.

From this gentleman.

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Lots of help here for you . Have you checked the vent lines in the mold with a glass? If obstructed take a fine scribe and from the cavity out clean them to remove any fine lead particles or burrs . Could have been from the original cutting of the mold. A fellow shooter just bought a custom mold from a well known maker and it would not fill out on one side. called and wanted to get advise on it and the suggestion was to check the vents and it turned out to be that. Vent lines may be put on blocks before the cherry  or lathe cutting process. Just one more idea.

In regards to electric casting furnaces. I know lots of people use them with great success. It is my experience that a more even consistent heat may be obtained by using a natural gas or propane burner. One that will produce 15000 BTU's is capable of heating a 12 pound pot to over a 1000 degrees.  Single burner cast iron hot plates are very inexpensive. A 40 pound bottle of propane will cast a billion bullets.  If you don't want to be limited by the thermostat this could be the answer.