help with mold problem needed

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  • Last Post 25 October 2022
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sluggo posted this 24 October 2022

Hello: I am having trouble with one cavity of a NOE bullet mold. It is a two cavity gas check and plain cavity .311 mold. The plain base side for some reason has a small defect near the tip. This does not happen in a row. but out of 80 bullets cast, 20 had this defect. any idea what is causing this? I like the mold but there are too many culls for me.Thanks for any help on this. 

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Ross Smith posted this 24 October 2022

The fill out on your bullets is not very good. All the "sharp" corners are rounded . Perhaps more heat and or more tin in the alloy?

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Duane Mellenbruch posted this 24 October 2022

If you are using a bottom pour pot, wipe off the drip on the nozzle and then pour rapidly to fill the mold.  If your casting alloy is too cold, that can also be an issue.   I keep a pot temp at 720 for alloys with antimony in them.  The mold blocks are aluminum and appear to be of fair size so might need more heat and a bit faster casting tempo to resolve the nose defects and the rounded bases.  Are you forming a large sprue puddle?

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RicinYakima posted this 24 October 2022

What Duane said. More heat and cast faster.

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Wm Cook posted this 24 October 2022

Agreed. Best guess is that’s a cold mold. Try preheating on a hot plate plate >400 then maybe pick up the pace short of base tearing or smearing on the sprue plate. Driving bands and base should have a sharp corner.

Once you get it dialed in keep that same constant pace (5 to 25 seconds, it varies by aluminum, brass and iron) between pour and sprue cut. A clock with a sweep second hand helps.

What you get will be more than .5 or more grains heavier than what you’re getting now. Good luck, Bill C

Patience isn’t a virtue, it’s a delay tactic.

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David Reiss posted this 24 October 2022

Same as Duane and Ric said. Definitely a mold fill issue, not a mold defect. 

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Rich/WIS posted this 24 October 2022

What they said.  A bottom pour can sometimes have a small drop on the the bottom of the spout that will not remelt if dropped into the mold and leave a spot like that, 

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sluggo posted this 24 October 2022

Thanks for the suggestions boys. I will put them to use the next casting session. I was alternating with another mold when this occured. Also i was filling the plain base side first, then the gas check next. That might explain why the gas check bullet formed better than the plain base one. Next time i will just use the one NOE mold. Thanks again and stay safe, mike.

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Eutectic posted this 24 October 2022

Those nose defects are a symptom of cold alloy at the start of a pour. I release a little alloy into the tray before I fill the mold, this gets hot alloy into the nozzle. That drip on the nozzle causes nose defects. 

I run the pot 50 F over the liquidus temperature and adjust the mold temperature with casting speed or heat addition.

I can run two iron molds simultaneously, but I have not been able to do that with aluminum molds. Aluminum molds need to be run hotter. You might get some smearing on block tops or sprue plate at the higher temperature. A 6B art pencil will apply graphite to prevent this. 

The mold blocks look lovely, it is not a mold problem.  

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sluggo posted this 25 October 2022

I would like to thank everyone for steering me in the right direction on the NOE mold. The bullets are coming out great after making the suggested changes. This is the first aluminum mold i have owned since a Lee .38 cal. mold years ago. All my molds are steel or brass. It seems an aluminum mold heats up fast and cools off just as fast! Now i hope these new bullets will work well in my 1898 Krag and Remington 1903A3 . thanks again, mike

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