The "drop weight" of a bullet from a mold will vary due to different things. Tolerance of the individual mold is one, casting technique can be another, but the biggest reason is normally the alloy being cast.
I don't know about other makers, but Lyman tells you in their manual that the nominal bullet weight their molds produce is based on using their #2 Alloy.
Its just common sense that casting a different alloy, with different percentages of lead, tin, and antimony will result in a different bullet weight coming out of the mold.
I don't know about other makers, but Lyman tells you in their manual that the nominal bullet weight their molds produce is based on using their #2 Alloy.
Its just common sense that casting a different alloy, with different percentages of lead, tin, and antimony will result in a different bullet weight coming out of the mold.