A friend of mine has a peculiar bullet sizing problem with his .44-40 (.427") bullet sizer. We have tried to figure it out what the cause is but were not successful yet.
He uses a .427" Lee-lube-sizer to size his .429" bullets back to .427". This on it self is no problem with ready made factory cast bullets. Also all our home made cast bullets with a lead-tin mix (98%-2% and 95%-5%) do size back perfectly at the correct diameter.
But now the problem: if we use “pure” (100%) lead bullets and we size them with his Lee-lube-sizer they all come out at .425", why does this happen? I did size the bullets also with my RCBS Lube-A-Matic using the .427" sizer and than all the bullets come out exactly .427". This problem only occurs with pure lead bullets with the Lee bullet sizer.
We did tried it with lubed bullets (Lee liquid Alox, our home made bullets lubes and SPG lube) and pure plane (without lube) bullets. The problem stays the same, lube or no lube it does not matter. Neither the bullet designs nor the bullet weights are the cause The pure lead bullets (in all shapes and weights) do get way much smaller in diameter than intended with his Lee bullet sizer.
Okay we could use the regular lead & tin mix but for some local (Dutch) steel plate (SASS) competitions we are only allowed to use pure lead cast bullets.
Stampede