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Pure lead for air gun pellets melts at 622 degrees F (621.5 to be exact)
About the same if you are running a tiny bit of tin 1-2% as some people tend to like to do…
Thus all you really need is ~ 700 degrees of heat to melt the lead … Too hot a pot, & one can tend to start to tend to warp the brass moulds, & tend to decrease the life of the aluminum ones…
For me the moulds are tools… it’s like anything else… if you take care of your tools, they will tend to last longer than you will…
You will I believe find that the longer that the sprue puddle takes to cool is a potential gauge on how hot you mould body itself is getting…
I have a separate pot for BP & airguns setup with soft alloy… mostly pure lead for the BP shooters…
Also separate pots for the medium to harder alloys… for different cast bullet applications, & different product…
I’ve found in either case… that waiting until the sprue on top visually seems to cool, (You can see the visual change) … That is for basically long enough to get good product, without causing lead smears on top of the mould body…
Not waiting for the sprue puddle to cool is an easy way to get lead smears on the top of the mould body…
Thus one can get a pour cooled, dropped, & basically be ready for the next run in about 20 seconds… So roughly 3 to 3.5 pours per minute…
When and if the cast product… starts to show some frosting … then … (for me) … it is basically time to let the mould cool a down tiny bit…
Some individuals like the frosting … Some do not …
Your call … on how you want to handle any or all of the above…