Diameter differences of cast bullets

[plaz]

When you cast bullets from the same mold you get bullets with slight differences in diameter. Sometimes the diameter is too small to be accepted.

What is the cause of these diameter differences out of the same mold? Do we know what causes the diameter to be greater and what causes it to be lower?

[jsizemore]

plaz, consistency in casting will produce consistent boolits. Temp of the lead, temp of the mold, rate of pour and time to solidify and cut sprue all contribute to consistent boolits. Each alloy and mold will tell you what it takes to end up with quality. Watch videos of automated casting machines and you'll get an idea. It don't hurt to have a watch or timer handy to learn the timing/rythmn for casting consistent boolits. Any mistakes can easily be hidden. Good Luck

[Spector]

Also multiple cavity molds may produce different boolit diameters from mold cavity to mold cavity even if everything else is spot on in your casting process. Mold cavities can be lapped to increase diameter uniformity among cavities, though you may still have boolit weight variations from cavity to cavity.........Mike

[mooman76]

Sometimes also after you have been casting durring a long section, you will get tiny lead splatters inside the mould that keep it from closing all the way. This can be a good thing at times as it is accidental Beagling.

[Shiloh]

Consistent, repetitive technique produces consistent boolits. They may however, vary slightly in weight from alloy to alloy. Just like shooting, doing it the same way with each shot gives your best results.

Shiloh

[243winxb]

A higher percent of Antimony in the alloy will increase bullet diameter as it drops from the mould. Linotype is a good additive also.

[qajaq59]

Scrounging wheel weights and lead from various sources can lead to different alloys, and may cast just a bit different. Not much you can do unless you buy your lead certified, and get a big batch. I just size em and don't worry about it.

[Centaur 1]

What I've noticed is that the boollits get progressively larger as the mold heats up. The metal expands as it gets hotter, which make the mold cavities grow also. It's probably less noticeable with a steel mold, but my Lee aluminum molds seem to be prone to this.

[leftiye]

Whereas mold and/or melt not being hot enough is a cause of poor fillout, a too-hot mold interferes with the alloy freezing and the boolit shrinks instead of drawing lead from the sprue pool, causing variations in undersized boolits.

A little frosting, not too much with your wheelweight and lead alloy boolits.