lee molds v rcbs

[loiner1965]

i cast a few bullets in different cals and ordered a few sizing dies from a forum member and measured a few bullets to check....most of my molds are lee and to be honest they cast perfect and more or less as stated...now i love my rcbs martini mold but it casts at .465 instead of .470 as stated.
i tried to cast different tonight by not water quenching but air drying the bullets to see if they shrink back different but they were no difference..
the lead is pure and soft but i am not bothered about the weight just the size
might try and add linotype to the lead or tin to harden up as been told they tend to cast bigger....not fussed as the old martini shoots great at .465 with my old eyes directing the bullets

[markH]

First question is have you slugged the barrel to see what size it actually is. 19C quality control isn't always as tight as more modern guns.

If it is .470 you might try teflon patching. High density tape is a bit thick at 5thou but the standard plumbers thread tape only measures about 1 thou so a couple of layers would bring you up to the required diameter.

Also keeps the barrel nice and clean.

[Simon G]

The size of bullets thrown from a mold are given for a #2 alloy metal mix. Pure lead does shrink more when cooling. Try some linotype to bring your lead up closer to an alloy, as you have said, that may very well increase the size of your finished bullets.

[loiner1965]

cheers lads.....shoots great as they cast to be honest just wondered why the lee mold under the same conditions csts spot on.
was told that rcbs molds are calibrated using hardened lead