Mold Personality

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Last Post 29 November 2024
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Aaron posted this 17 November 2024

Today while casting with my Lyman 358439 hollow point 38 caliber mold, I was reminded yet again that molds can have "personalities" (idiosyncrasies). This mold simply will NOT fill out the bullet base regardless of alloy temperature, mold temperature, alloy composition, mold position, Latin or English prayers, ladle poured dribbling, ladle poured coupled, dribbled from a bottom pour pot, or any other method EXCEPT coupled (mated) to a bottom pour pot. Period.

I know. I know......increase the temperature.

880 degrees should be hot enough right?

Here is the base of the bullet in the mold with any filling method except direct contact with the nozzle on the melt pot.

Here it is using contact with the melt pot nozzle. Perfect. The spot in the middle of the base is a trick of light, not a depression or rip.

It goes to show how a specific mold behaves differently than other similar molds. I am fortunate in that I have several pots to play with, including ladles to pour with. I can vary temperature, alloy and other variables to determine how to address each mold. I feel so sorry for folks who have one or two molds and limited tools to use to get things working for them. We usually see posts from new casters who are extremely frustrated when a mold will not cast correctly. We offer advice which hopefully works but there are some molds that just need pampering with tools that new caster may not have.

With the same alloy used in the Lyman mold, my Accurate Mold for the 32-20, the AM 31-120I, cast beautiful bullets from the get-go with the ladle. That mold likes a mated ladle to feed it and will cast with the bottom pour spout on the Lyman pot, but burbs up voids when fed that way. Again, a completely different personality between the two molds.

I still have to figure out what is causing this anomaly though.

All in all, I had a wonderful casting session this afternoon. I have a lot of pills for the 32-20 revolver, and even more HP pills for the 38/357.

AM 31-120I bullets

....and Lyman 358439 Bullets for the 38/357

I just love the end result of a good casting and loading day!!

With rifle in hand, I confidently go forth into the darkness.

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CBA Member

Aaron posted this 17 November 2024

So you know, the COAL of the cartridge above with the AM 31-120I is 1.655" which may not feed in any 1866/1873/1892 lever action rifle. Cases could be trimmed shorter to make the COAL at or less than 1.60" if you really like this bullet. I got it for my revolvers in 32-20. I don't have a lever action in this caliber. Yet......

With rifle in hand, I confidently go forth into the darkness.

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RicinYakima posted this 17 November 2024

There is not enough venting between the sprue plate and mould, or the parting line of the mould halves.

Once the liquid gets up to the base band, there is no place for the air that is left to go. By pressure casting, you can get most of it out.

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Aaron posted this 17 November 2024

Ric, I loosened the plate right off years ago. I thought the same thing. It had no effect. Still no fill out. Tried all the tricks. This mold just likes to be force fed. Fortunately I can feed it that way.

With rifle in hand, I confidently go forth into the darkness.

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RicinYakima posted this 17 November 2024

You are right, they all have their personalities.

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OU812 posted this 17 November 2024

Most all of those bullets look like they dropped from cool mould. Dip the mould corner or end in melt to get it HOT. You can also get mould too hot, but wait for sprue to solidify before opening. Loosen sprue plate so that it swings open very easily, almost flopping open. Work faster to keep mould up to hot temp...there is a sweet spot. Hope this helps. I also have a couple of difficult moulds that are not easy.

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singleshot posted this 17 November 2024

You can vent the top of the mould by stoning or lightly filing a .005" chamfer along the facing edges of the mould blocks.Charlie Dell did this to all of his moulds and it really helps filling out the bases.

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Match Director

linoww posted this 18 November 2024

my ocd buddy keeps notes on each mold on their peculiarities. I have too many molds (and lack of organization) to do that

"if it was easy we'd let women do it" don't tell my wife I said that!

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Wilderness posted this 19 November 2024

I have a WRACo .32-40 mould (no venting grooves) that was producing a lot of flaws on the body of the bullet. This was with mould in left hand, rotated 90 degrees to the right, dipper in right hand, join, then rotate upright.

I fixed it by holding the mould upright on the left-right axis but with the front tipped down, then join dipper and bring the mould to upright.

I reasoned that casting like this kept the join on top where it could vent.

Insomniac, agnostic, dyslectic - awake all night wondering if there is a Dog.

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Aaron posted this 19 November 2024

Interesting. Picturing this spatial gyration led me to wonder if anyone makes a left-handed dipper, the use of which would make a left-handed sprue plate a necessity too so one would not have to shift hands every cast.

I guess all you south-paws just have to deal with the right-handedness of the tools - like scissors. A custom mold maker like Accurate could change the orientation of the sprue plate I think. Drill the holes across the mold top and rotate the sprue plate upside down before drilling the feed holes.

With rifle in hand, I confidently go forth into the darkness.

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Aaron posted this 19 November 2024

Just discovered that Lyman makes a lefty ladle. I learn sumptun every day?

With rifle in hand, I confidently go forth into the darkness.

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Aaron posted this 19 November 2024

Willis,

Are you referring to these lines when you suggest breaking the edge?

With rifle in hand, I confidently go forth into the darkness.

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RicinYakima posted this 19 November 2024

I was. Yep.

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Aaron posted this 19 November 2024

I hit them with a stone. I'll cast again soon with this one to test it.

With rifle in hand, I confidently go forth into the darkness.

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singleshot posted this 20 November 2024

I was. I'll bet it helps.

Willis

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Aaron posted this 26 November 2024

You can vent the top of the mould by stoning or lightly filing a .005" chamfer along the facing edges of the mould blocks.Charlie Dell did this to all of his moulds and it really helps filling out the bases.

I actually listened and followed this suggestion by showing the seam a jewelers stone. It worked. With the knife edge broken and the seam joining up with an almost imperceptible bevel, the bullet bases fill right out with a ladle pour. Granted the ladle needs to be 80% full but it works.

As a side note, I bought a Lee #20 Production Pot to blend 20:1 in. I set the thermostat on #8 and let her rip. After a few good csts, I put the Lyman thermometer into the alloy. It PEGGED the thermometer at 1000 degrees !!!!

Setting the thermostat to #6 had no effect on lowering the temperature. Apparently this pot has two speeds. Dead stop (cold) or afterburner (wide open). Oh well. such is life. I can deal with it.

With rifle in hand, I confidently go forth into the darkness.

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RicinYakima posted this 27 November 2024

I have two Lee pots, and run both from a PID controller. My old 10 pound varies almost 250* from heat on to heat off. The little 4 pound pot only varies 100*s. And I'm sure you know that the numbers on the thermostat have nothing to do with the temperature of the lead in the pot.

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Eutectic posted this 29 November 2024

I have done this on several molds with base fill problems and it works! You must be careful, only a tiny chamfer is needed. Too much will get you whiskers on the base. Do one edge first and see if this is enough.

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