Friday, March 22, 2013

Boolit shrinkage

Cast Boolits - Dedicated To The World Of Cast Bullets!

Ok...here's hopefully going to be a good debate. 5-6 weeks ago I cast up a bunch of boolits for my 45-70. 300gr, 405gr and 425gr.
About a week after, I sized, lubed and GC'd about 50 of each. All 3 molds dropped at .460, and i sized to .459.
Pot temp was 700*, all my casts were from the same melt.
The 300gr mold is iron, the 405gr is brass, and the 425 gr is aluminum.
Today I loaded up some of the 405gr, ran out and needed to size some more.
The shank has shrunk to where the GC's fall off, even after being sized. But they still are .460 on the driving bands.
So I switched over to the 425's and had the same problem. Shank shrunk, but driving bands are .460.
So getting the scratching my head syndrome, I checked the 300gr casts.
Size .460, shank was tight on the GC's.

So why is if temp stayed the same, melt was the same, casting rhythm was adjusted for the different molds to throw slightly frosted boolits, would the shanks on the 405 and 425 shrink, but the driving bands stay the same .460, but the 300gr is still good to go??

New or different lot or maker of gas checks, perhaps? Gas check shanks and their relationship to GC material and thickness is one of those *nice* little variables with which we must deal on occasion. Checks do vary slightly, even from the same maker at times.
History is always ambiguous, if honestly presented--Stephen E. Ambrose
No no variance...they are all from the same pkg, Hornady. But why go on back 5 weeks or so ago and not now??
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Pointed Soft Point "Core Lokt"


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