Casting question

[Ken Hansgen, 11094]

Was casting bullets this morning with a Rapine Wadcutter mold, #575470. When weighing them with a digital scale, I found bullets from 465 grains to 496--quite a spread--tho' most were in the 469-471 range. The heaviest were cast early, while the mold was heating up, and they got progressively lighter as it got hotter. Since this is the exact opposite phenomenon from my earlier casting experiences (mostly with conicals--they go from lighter to heavier) I grew curious. Why?

[Pat in Virginia]

Ken,

Perhaps there was a bit of fouling on the mould that kept it from closing completely; hence a bigger/heavier bullet than when it is does close completely. As the mould heated up, if the obstruction was lead, perhaps it melted away. If the obstuction was some other form of trash then perhaps it fell out as you worked the sprue cutter.


If you still have the heavier bullets look at them and see what they are like along the line where the blocks join. Are the lines wider? You can also measure the diameter of the bullets with your calipers to see if they are bigger (on one side or both) where the mould blocks come together.


Pat

[Rich Foster]

Maybe your muscles got stronger while casting and you were holding the mould blocks tighter together.
Your mould pins has probably worned lining up when hot casting bullet after bullet and probably not lining up when just starting to mould leaving it slightly open.

[Ken Hansgen, 11094]

I threw the heavy bullets back in the lead pot, so don't have them anymore. Will check your theories next time I cast. Thanks for replies.

[Ken Hansgen, 11094]

Cast yesterday am with same mold. Had a much smaller range this time around 470 w/o the phenomenon described above. Think now Pat got it right--there was some lead or something keeping the mold from closing completely. No, Rich, I'm not that strong, tho' I did start holding the mold handles rather tight!