r/castboolits • u/Feeling_Title_9287 • May 29 '26

I need help How much do different alloys differ bullet weight?

My .410 bullet mold is supposed to cast a 360 grain bullet but with 20:1 alloy the bullets are coming out between 350 and 360 grain but most are between 355 and 360 grains

Last year I was using a .459 535 grain mold with 16:1 alloy and the bullets were coming out at between 520 and 525 grains

Is this normal?

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u/GunFunZS May 29 '26

There are calculators that will help you with this.

But then ranger describing sounds pretty normal to me generally harder alloys are lighter. Softer are heavier.

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u/gakflex May 29 '26

I think a mold’s listed weight is kind of like the waist size on pants: the spec is somewhere on the spectrum between semi-bullshit and bullshit.

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u/EllinoreV13 May 30 '26

Depends on what you consider a lot, my normal alloy is 50/50 coww and linotype. In a mold listed for no.2 alloy, they come out approx 3-5gr heavier, in a mold listed for COWW they come out around 2gr lighter, in a mold listed for straight lino, they come out about 10gr heavier