Sorting Bullets From a Two Cavity Mold For Accuracy

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CBA Member

Wm Cook posted this 7 hours ago

Has anyone documented the +/- benefits to accuracy by sorting bullets from a two cavity mold? Example; 311299, 314299. Thanks, Bill Cook.

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CBA Member

fc60 posted this 4 hours ago

Greetings,

The only documentation I have is that each cavity is slightly different in shape and weight.

I have a SAECO RG4 that the previous owner placed a small prick punch mark in the grease groove of one cavity. It was also marked on the opposite block to, in theory, maintain the balance as it spins.

I can now sort my bullets by cavity.

Weighing each bullet makes more sense when you are measuring the same cavity.

Cheers,

Dave

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CBA Member

Wm Cook posted this 3 hours ago

I’ve heard of a prick punch on the driving band but not in the groove. Theory being that sizing the bullet will wipe off the prick mark. I have a 225438 that drops about .3g / .4g different front to back but for practical use with a Hornet or a K Hornet the 45 grain 225438 would never ever show any difference.

But if I were casting for high end accuracy, competition, the difference in the two cavities might make me think a bit.

A lot of folks that shoot competition use single cavity molds for just this reason. But I’m certain that some are using double cavity molds. Specifically those shooting Lyman’s silhouette bullets like the 311299, 314299.

I was just wondering if anyone ever ran a trial to see if it was worth it, and if so, where did they mark the mold. Probably a stupid question. Thanks, Bill.

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RicinYakima posted this 3 hours ago

Actually, a very good question.

Severall of us solved the problem but simply making them the same. We cast linotype bullets and polished out the cavities. Cast from F was used to polish B and vis-versa. This was repeated back and forth until we couldn't measure any difference in size or run out. Using 600 grit valve compound and doing it by hand only took a couple of hours.

FWIW, Ric

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Millelacs posted this 2 hours ago

I have some molds with marks in them. One punch near the nose for the front cavity and two marks for the rear cavity. Then it’s easy to segregate the bullets by cavity. I load by cavity.

With the marks near the nose, the sizing and seating process’ flatten out the marks to where they are almost not able to be seen.

I found that a center punch works better than an awl.