Iron, Brass or Aluminum Molds

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Wm Cook posted this 21 June 2025

Do you have a prejudice whether the molds you buy are made of iron, brass or aluminum? Looking forward to some input from those that know more than me. Bill.

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Bud Hyett posted this 21 June 2025

Preferences:

  • Iron: One- and two-cavity molds, most heat-stable in a long casting sesssion, rust can be a problem for long-term storage. Many different iron alloys, I prefer meehanite for heat stability.
  • Aluminum: Four-cavity pistol bullet high-production molds, lighter weight not as tiring when I want many bullets. You need to regulate the pot heat closely for weight consistency.
  • Brass: Very good mold material, but selom seen. Mostly custom mold makers of which I have several single-cavity molds. I have one four-cavity brass mold that is very tiring to use.

Farm boy from Illinois, living in the magical Pacific Northwest

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MP1886 posted this 22 June 2025

Preferences:

  • Iron: One- and two-cavity molds, most heat-stable in a long casting sesssion, rust can be a problem for long-term storage. Many different iron alloys, I prefer meehanite for heat stability.
  • Aluminum: Four-cavity pistol bullet high-production molds, lighter weight not as tiring when I want many bullets. You need to regulate the pot heat closely for weight consistency.
  • Brass: Very good mold material, but selom seen. Mostly custom mold makers of which I have several single-cavity molds. I have one four-cavity brass mold that is very tiring to use.

Bud apparenty you haven't bought any of Mihec moulds the guy in Slovakia.  That's his number one material, but he has other metals too. 

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Wm Cook posted this 22 June 2025

After buying a string of 8 or so brass molds in the past couple years (MP & Accurate) I’m going to shy away from brass. I had a brass single cavity warp from excessive heat. It was my fault. I was ladle casting too fast. Tom clearly has it on his web site that excessive heat can warp brass molds. As far as I can tell, bottom pouring will never get a brass mold hot enough to warp.

So for now all of the single cavity competition molds will be iron which I think was Bud’s first choice. Bill.

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MP1886 posted this 22 June 2025

After buying a string of 8 or so brass molds in the past couple years (MP & Accurate) I’m going to shy away from brass. I had a brass single cavity warp from excessive heat. It was my fault. I was ladle casting too fast. Tom clearly has it on his web site that excessive heat can warp brass molds. As far as I can tell, bottom pouring will never get a brass mold hot enough to warp. So for now all of the single cavity competition molds will be iron which I think was Bud’s first choice. Bill.
On the brass molds you said you warped. Didn't you notice any indications that it was too how like taking the sprue long to get hard or very frosted bullets? Also if you want to cast faster I'm sure you are awave of a little overhead fan blowing on the mold?

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Wm Cook posted this 22 June 2025

“ Didn't you notice any indications that it was too how like taking the sprue long to get hard”

Nope, not that smart. After the sprue frost, (how ever long that takes) it’s simply one Mississippi two Mississippi….to what ever it takes for a clean (no tear, no smear) sprue cut. Then repeat at whatever that cadence happens to be.

Frosting is common for me when casting for accuracy. I usually run a mold temperature of 375 to 400 depending on whether it’s bottom poured or if it’s ladle poured. I don’t care what the temperature is, I just lock into a steady cadence and spot check the mold. Now if I had another 5 years under my belt I wouldn’t need to peek at the mold temperature, but I’m still learning. And obviously still making mistakes.

In this case I was ladle casting a normal 2 hour session (~140 bullets) in one stretch and I went brain dead. I think the same thing would happen on a hot plate if you’d get sidetracked with other issues and don’t keep an eye on things.

I think brass makes a great mold. I just have to be careful when ladle casting. Bottom pouring you can rock & roll. But I believe with ladle casting, depending on how much overflow you have built into your cadence, can get you in trouble with brass.

I’ve got two of the three molds I’m working with for this rifle already converted to iron.

Maybe I’m wrong on these assumptions??

Personally, I’d recommend iron for bullet quality and having a mold that will last a lifetime. But for high volume and good quality NOE’s aluminum molds would be my choice.

I’d appreciate any input. Bill.

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Aaron posted this 22 June 2025

I have all three and use all three. Can’t say I have a preference although the brass molds sure are purdy.

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

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MP1886 posted this 22 June 2025

I've had aluminum molds for decades with no problems of getting beat up.  I use a PID controlled pot and keep a very constant temperature.  Bill your temperatures you said you are casting, is that pure lead because that's a mighty low temperature. Bullets that are frosted are not the same in dimensions and weight/densitey then proper cast non frosted bullets. 

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Wm Cook posted this 22 June 2025

“ Bullets that are frosted are not the same in dimensions and weight/densitey then proper cast non frosted bullets. ”

Would that contribute to being out of round on bore riders? At one point I almost reached the conclusion that alloy running 680 & mold at 360 cast more round. Not enough data to prove anything.

I run the alloy almost exclusively at PID controlled 710 and the molds between 375 and 400. 90% of the time I cast with Linotype. The exceptions to that are 9mm, 7.62’s & .22’s where #2 alloy is used. Bill.

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pat i posted this 22 June 2025

I like aluminum molds. LBT, NOE ,and Accurate. Even Lee and never had a problem with either the molds or frosted bullets and I've cast thousands of them Saying a frosted bullet is a not a "proper cast bullet" is flat out wrong as long as theyre frosted all over. I've shot plenty of frosted and not frosted bullets and if someone can SHOW me (not repeat what they think or heard) they aren't as good as nonfrosted bullets I'm all ears.

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MP1886 posted this 22 June 2025

I like aluminum molds. LBT, NOE ,and Accurate. Even Lee and never had a problem with either the molds or frosted bullets and I've cast thousands of them Saying a frosted bullet is a not a "proper cast bullet" is flat out wrong as long as theyre frosted all over. I've shot plenty of frosted and not frosted bullets and if someone can SHOW me (not repeat what they think or heard) they aren't as good as nonfrosted bullets I'm all ears.
There is a difference in shooting them and getting accuracy then just shooting them. I bet you're all ears.  You're the negative 3 Musketeer "All for one and one for NONE".  Again I say find out yourself. 

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pat i posted this 22 June 2025

Having spent years past shooting CBA matches all over the country and being the director of registered competition for a few of those years I have a pretty fair idea of what accuracy is. The difference is my accuracy standard is based on time at bench some people's is based on time at the keyboard.

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MP1886 posted this 22 June 2025

Having spent years past shooting CBA matches all over the country and being the director of registered competition for a few of those years I have a pretty fair idea of what accuracy is. The difference is my accuracy standard is based on time at bench some people's is based on time at the keyboard.
LMAO only people of your caliber use BS terms like "keyboard"  brought in by the computer age with a whole bunch of other woke words. Hey I'm finished there are a lot of good people on this forum that wish to further their knowledge rather then watch us duke it out.  They know about you.....adios

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pat i posted this 22 June 2025

Bye love, have a nice day. Keyboard is a "woke" word???

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Capt45 posted this 22 June 2025

I think he misspoke, probably meant to say were dating yourself.

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pat i posted this 22 June 2025

I think he misspoke, probably meant to say were dating yourself.

Maybe but dating myself beats the hell out of the alternative.

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Tom Acheson posted this 23 June 2025

I posted this in the wrong area but it was intended for here....

 

My large bullet molds are single cavity, iron/steel. One is a Paul Jones and the other a Saeco.

My best .30 caliber mold is an aluminum LBT 2-cavity. Not far behind is a Don Eagan single cavity brass mold.

My .22 mold is a brass NOE 4-cavity. My .38-55 4-cavity brass mold is by Accurate.

All mold alloys have served me well, no stand out preferences.

Tom

 

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OU812 posted this 23 June 2025

I like the lighter weight NOE aluminum moulds, but do not overntiten hinge pins. This will cause mould to bow and distort.

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Shuz posted this 23 June 2025

By hinge pins, are you referring to the pins or screws that hold the blocks to the handles?

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Aaron posted this 23 June 2025

Well I have shot thousands of "frosted" bullets and thousands of non-frosted bullets. Can't say I have seen any difference. Binary alloys tend not to frost even at high casting temps like 850+. Alloys with antimony and arsenic will frost over if temps get too high. All of them size up fine in the lubrasizer and the frosted ones have that cool two-tone look to them. Three-tone with the lube in there.

Don't see why it matters actually. The barn door has plenty of holes in it from both frosted and non-frosted. The game I have taken with frosted bullets both in rifles and handguns did not complain at all. I did see one buck shiver a little bit as it was evaluating the performance of the frosted bullet.

 

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

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Wm Cook posted this 25 June 2025

What gives up heat faster; iron or brass? Bill.

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