bullet diameter vs alloy

  • Last Post 18 March 2018
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Ross Smith posted this 18 March 2018

I know this has been posted but can't find it. Does lead cast a bigger diameter than WW?

Also, I was having trouble with wrinkles today on a new mold. I tried BARREL BLASTER gun cleaner and that my friends gets rid of grease and oil pronto. Use out doors, it stinks and is very harsh on skin. Probably very similar to brake pad cleaner.

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BigMan54 posted this 18 March 2018

Wish I knew. I've cast many a bullet of pure lead to push thru a cylinder chamber or bore. But never thought to measure one beforehand. But I think the harder the alloy, the bigger it drops from the mold. 

How hot is your alloy ? I always go 750-800 degrees with a new mold, supposed to help burn out/season the cavities.

How hot was your mold when you started pouring ? I like to cast as fast and as hot as possible on a new mold. About a hundred or so frosted bullets.

How long did you boil the mold ? I do it for 20-30 minutes. Losts of DAWN, Adding more soap and water as needed.

Did you scrub out the cavities with a clean brush ? 

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

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BudHyett posted this 18 March 2018

An alloy will be larger since the alloying agent will disrupt the crystalline matrix. The alloy molecules sit within the crystalline matrix and push aside the neatly ordered array of the lead. This expands the bullet in size. Even when the molecule is smaller than the lead molecule, the disruption of the structure  causes the growth. 

In the Lyman Cast Bullet Reloading Manual, there is an excellent article on alloy and the effects of alloying. 

Country boy from Western Illinois, living in the Magical Pacific Northwest

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onondaga posted this 18 March 2018


The wrinkles are a symptom your thermodynamics are cool also. The casting defects from petroleum gassing out are different than wrinkles. The gas causes dent like defects, not wrinkles.When you are happy with cleaning your mold, Here is a suggestion:

    Determine the ideal pot temp for your specific alloy with a thermometer. 100 degrees above fluidus is the ideal. Heat your alloy all the way hot with a thermometer in and cut power. Record the temp at the first sign of surface solidification. Add 100 to your recorded solidus temp. and set your pot to that. Using a 1 or 2 cavity mold you should cast to drop 3 times a minute or better and your thermodynamic problem is GONE and your mold will also be casting maximum diameter for your alloy. Your bullets will appear velvety indicating max diameter, Shiny is from cold casting and will be smaller than max diameter for the mold. This is valid for both ladle and bottom pour casting.



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Ross Smith posted this 18 March 2018

Judging from the cooling sequence of the sprue, everything was hot enough, just not clean enough. I washed the mold which was brand new, then went to casting. I expect a few wrinkled cycles till everything is up to temp.

The point was and still is, Barrel Blaster  will clean your molds, pronto. 

Thanks for the reminder that alloy expands the diameter. Gonna go try pure lead to see if I can get a tiny bit smaller and softer bullet for breech seating.

ps: It worked!

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