Thanks for everyone's replies! I just purchased the Lee 4-20 pot, Lee .530 mold, One of the halves is loose though, I was told this is the way they are. I also purchased a Lyman Digital Lead Thermometer but I have to send it back. The thermometer is 5 degrees low(60) at 65, and 7 degrees low (205) at 212.
You made a good choice from my perspective.
I own a pair of the Lee 10# bottom pour production pots, the 4-20 bottom pour as well as a Lyman "Big Dipper" picked up at a garage sale, and a cast iron plumbers pot and ladle inherited from my uncle, who was a plumber back in the day, when they used such stuff often.
I cast all manner of projectiles, handgun and longarm, modern and traditional, and by far, my go to is the Lee 4-20. If I am in for a particularly serious session and am working with more than one metal/alloy I will start up one or both of the Lee 10#s as well, and/or use the dipper furnace to have metal ready to top up the bottom pour to save waiting for cold metal to come up to temp.
I have had minor issues with leaks, generally on start up, but if well maintained and the spouts kept clean, a tweak here and there (as with the screwdriver slit mentioned above) will correct any problems. It is best to not let the level of the metal get low enough that any floating impurities might find their way to the spout. That can, after time create leakage problems.
The idea of a thermometer is a good one. I was going to suggest that prior to reading your post, and a analog one will do as well. They become particularly useful when working with alloys beyond pure lead, and will tell you a a lot about the mixture in your pot, as well as helping to set that "sweet spot" for easiest and most efficient casting with pure lead or other alloys.
It is true that one side of the mold will be "loose" to aid in alignment while casting. Also make sure to heed the instructions regarding cleaning and lubricating your mold prior to use, as it is essential to "running good ball". I usually degrease mine when new, by washing in hot soapy water, scrubbing with an old toothbrush, and then wiping with 90% rubbing alcohol on a Q-tip, but have used brake cleaner and carbureter cleaner prior to the alcohol as well. Generally I use a stick of "Alox" type bullet lube to lube my molds once warm, and also use pea sized chunks of it as a flux.
Preheating you mold by placing on top of the pot will shorten the time to dropping good projectiles. You also may need to set it aside fore a couple of moments and let it cool, as after a while the balls may become frosted as the mold heats up excessively. It can be handy to have a small squirrel cage type fan handy (from and old appliance or such) to help facilitate this cooling, or better yet a second mold that you can rotate with, and as it heats up, switch back and forth in an established rhythm.
Like I said, good choice from where I sit, and I believe it will serve you well for a long while.
