weight differences in lead cast bullets

Berry's Preferred Plated bullets begin as a swaged lead core. No air bubbles like cast. The cast weight will change using different alloys.

Variations in lead alloy composition will affect weight. And voids will reduce weight. Probably others as well.

When I weighed my own home cast bullets the variations tended to be a result of the divot at the sprue plate cut. Some times a cavity would form there and those bullets would be slightly lighter, otherwise they were very consistent.

Other problems could be incomplete fill out of the mold, varying alloys between batches of bullets and then mixed together for storage, some casters run machines with multiple molds and there could be small variations between molds or even variations between cavities in the same mold.

FWIW if all the bullets are the same length they should seat consistently therefore take up the same amount of space in the case which means pressure will be consistent and the tiny variation will never be noticed.

If they are lubed the lube can vary also.

BBarn said:

Variations in lead alloy composition will affect weight. .

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This here.
Tin and antimony used to alloy the lead are lighter than pure lead. If you casted 2 bullets in the same mold 1 pure lead and 1 a hard alloy the hard one will be lighter.

A year ago I had cast some 45-200LSWC bullets, weight separated and bagged them. The majority of the bullets weight in one of two groups. A year later I casted another batch of 45-200LSWC bullets with the same jacketed range lead sources as a year before. I still spiral poured my lead stream and kept the lead temperature consistent. My technique to tap my mold so the pins lined up better helps. I weighed those bullets and they fell within the same groups as the previous year. I guessed that there is slight dimensional difference in my Lee gang mold. I don't think the heat of the solidified lead would make a difference since there is a 5 second difference between when I fill the first cavity and complete the last. The lead on the sprue plate is allowed to solidify before I cut the sprue off.

Docendo Discimus said:

This here.
Tin and antimony used to alloy the lead are lighter than pure lead. If you casted 2 bullets in the same mold 1 pure lead and 1 a hard alloy the hard one will be lighter.

Click to expand...

Which is also why swaged bullets tend to be more consistent than cast. There was a company called Alberts that sold discount swaged bullets for about 30 years. Their bullets were cheaper than electric for heating a pot of COWW’s (okay, that might be a slight exaggeration). I came across a few batches that had one or two bullets where the nose wasn’t formed perfectly but they still weighed right and flew right. It’s amazing how accurate “flawed” bullets can be.

I expect my cast to be within a grain across a session. I powder coat each lot a different color and load them in the lots that I cast. I do cross lots in some boxes.
Voids is the big issue. If you have a bullet with a void, weight, cg, and the rotational ballance will all be screwed up. If your bullets are over a grain different I'd make lots.

With the same 230 grain mold I can cast bullets as heavy as 240 grains using pure lead down to 211 grains using silver solder. Wheel weights drop at 232, and I can mix in Lynotype until they drop at 230, like “certified” lead does.

That said, the casting machines used for mass production run many molds, Magmas mark 8 bullet master, uses 8 molds if the mfg doesn’t have one of these, your getting bullets that were not even made with the same mold.





They do that because a single mold would get too hot, having many gives them time to cool between drops.

I measured my 44 mag 240 lswc and they varied around 15 thousands in length.

Also year 2 or 3 up or down in weight too which I don't worry about but the length diff I don't like. Just got mbc that I haven't measured yet.