temp

[batman]

how does a high temp affect bullet diameter higher the larger ,lower the smaller?

[lwknight]

Lead is kinda dead, temperature does not have profound affects in normal liveable ambient temps. Things like aluminum are a lot more highly affected by temperature.
The alloy has a lot to do with it as well. Impossible to say exactly.
Typically all metals expand as they get hotter. I think the temperature of your gun barrel will be more dramatic than bullet temperature.
Good idea for an experiment. Put one in the freezer and measure it cold then warm it up and measure again.

[montana_charlie]

I think he's asking what effect high or low 'casting temperature' has on bullet diameter after solidification...

[SciFiJim]

Actually, there is a phenomenon know as "shrunken band syndrome" that happens when casting with very hot alloy. All metal including lead, expands when heated. When the boolits cool and solidify they shrink a small amount. This is what allows boolits to fall from the mold with no tap or a light tap of a stick. The shrunken band syndrome is when the band area of the mold gets hotter than the rest of the mold. It has less mass to absorb the heat and heats up faster. It keeps the alloy hotter in that area for a brief amount of time allowing the other parts of the boolit to solidify first. As noted when casting the boolit will draw from the sprue and leave a dimple when cooling, it can also draw from the hotter band area as well, causing shrunken bands.

[HORNET]

This has been discussed a few times in the Molds forum. Look for posts by theperfessor, he did some experiments and was going to build some molds to get some more precise data. There's a mold temp/ melt temp interaction that goes on.

[batman]

thank you guys
that is what I needed to know.My bullets were coming out larger than I wanted.
Been shooting for .430 and getting .434 or larger.But when I turned up the heat the dia the dia went down to .432-.433. I just wasnt sure that was the cause or not.

[lwknight]

Shrunken band syndrome! hmmm that could explain a lot.
A good point to ponder anyway.