newby thermometer question

[corvette8n]

Got an RCBS dial thermometer, so what temps am I looking for while
casting using WW and a bottom pour Lee pot.
I usually throw a little block tin or lino in the mix.
I cast 308/150gr and 458/420gr from Lee molds.

[knothead]

I cast mine at 780-800 for the bigger bullets (520gn) and 760-780 or so for my pistol stuff.
I use ww and range lead from the indoor range 5 gal of ww to 80lbs of range lead = 20 to 1 or so says the lee.

[Buckshot]

..............Usually temps between 750 and 800 work well with WW. Tossing in some tin and/or lino will lower the good casting temp just a bit, but not enough for a guy casting by hand to notice unless you were at the low edge of getting rounded drive bands and other sharp features.

In my experience tempurature plays a bigger part in how fast you're casting, block material, how many and how big are the holes :-). In the recent group buy for a 6 cavity Lee dropping a .462" slug at 350grs, those blocks heat FAST. Gotta crank the heat down a little bit with that one.

...............Buckshot

[AZ-Stew]

Corvette,

First, you have to get the mould up to temperature. Almost any temperature over 750 will get you there in short order if you cast quickly. Don't worry about bullet quality for the first ten casts, just keep everything moving so you get a lot of heat into the mould quickly. I'm sure others will give you other methods for heating the mould, but casting is the method least likely to cause problems with the mould. Resting the mould across the top of your casting pot (not in the bullet metal) while it's heating up will shorten the initial "heat-up casting" process.

Once you get things up to temp and you're getting bullets that are completely filled out and wrinkle-free, turn the pot temp down to the lowest temp that will allow you to continue to cast perfect bullets, considering your casting style, workflow and rhythm. This will produce completely filled out bullets, with sharp corners and a nice shiny surface.

If you're getting frosty bullets, something is too hot. Turn down the pot temp or slow your casting speed. I've found that bullets that have a generally shiny finish, but with frosty areas, tend to be smaller in size at the location of the frosted spot. In other words, the frosty spots mark areas where there are recesses, or low spots in the bullet surface. Sometimes these imperfections are almost unnoticable, other times they're quite pronounced. I consider all such bullets to be defective, and return them to the pot for another go around. In any case, they're a signal that something is too hot and it's time to turn down the pot temp or slow my casting speed so the mould cools more between casts. You want to keep the mould at a relatively constant temperature. If it's gaining heat with each cast, you'll start to get frosted bullets. If it's losing more heat than is put back with each cast, you'll soon get wrinkled bullets with rounded edges.

The actual temperature number isn't as important as the quality of your finished bullets. If you continue to use the same alloy, knowing the temperature that gives you good bullets will help you get your next casting session going more quickly, since you won't have to search for the right temp by trial and error casting.

Regards,

Stew