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Thread: Cast Iron, Brass or Aluminium - What is your choice?

  1. #1
    Boolit Master Bad Ass Wallace's Avatar
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    Cast Iron, Brass or Aluminium - What is your choice?

    I've been casting for the last 50 years and beside the valuable experience, have accumulated over 120 boolit molds made of all different metals, steel, brass and aluminium.

    So what is best? I don't have one preferenced over the others.

    Steel molds are great for stability and consistancy; all my precision match grade and lathe bored molds are steel. Once set to casting temperature they can turn out tens if not hundreds of boolits with a variation in weight as little +/- 0.0015 grains. The finished cast diameter is also perfectly uniform.

    Brass molds are also good for precision boolts. Faster to heat to casting temperature but also by running alloy a little "hot", can gain almost 0.001" in size due to the difference in the co-efficent of thermal expansion to steel. If having a small break from casting the mold cools more quickly, so you may need to cast some dummies before beginning production once more.

    Aluminium molds, such as Lee, heat up quickly but also loose heat quickly if you casting process is not consistant. With molds over 30cal, casting with a 'hot' alloy can increase the finished diameter by 0.002". A good example of this is my Lee 220gn boolit mold for the 338WM, Cast hot it throws 0.3395" boolits 'as cast', perfect for the application.

    Hold Still Varmint; while I plugs Yer!

  2. #2
    Boolit Master
    Mal Paso's Avatar
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    Iron is first in my book but MP Hollowpoints only come in Brass and 6-8 cavities in current molds is always Aluminum so It Depends!

    I preheat all molds now. Brass 4 cavity and Aluminum 6-8 cavity are hard to start without a warmup.
    Mal

    Mal Paso means Bad Pass, just so you know.

  3. #3
    Boolit Grand Master
    bangerjim's Avatar
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    I own only TWO steel 2 cavity molds. That's enough for me. The rest of the "HUGE crowd" is mostly 2 & 6 cavity Lee Al molds and now 12 or so 5 & 6 cavity brass molds. You have not cast with pleasure until you use the 6 cavity HP molds in brass, unlike that single older "bottle stopper" style pictured above. The HP's just rain out of the mold! Very accurate and very repeatable.

    Brass does take more heat and stays hotter longer. That is why I am a proponent of electric hot plates to pre-heat all your molds (no matter the material) to FULL casting temp, not just warm, like on the side of a casting pot.

    My assortment of brass molds yields excellent precision castings every time. Many of the boolit designs I use only come in 2 cavity Lee Al design, so I have to live with that.

    No worry about rust with Al and Brass!!!! Just leave 'em laying in their boxes with no treatment needed.

    Any new molds I buy in the future will definitely be BRASS!

    Put another shrimp on the barbie and cast away!!!!!!!

    banger

  4. #4
    Boolit Grand Master

    Winger Ed.'s Avatar
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    I've only used Iron & Alum.
    They both work. But I tend to gravitate towards Iron.
    I just more comfortable with them, and I think they last longer without having 'issues'.
    Never ask old people how they are doing.
    Because they'll tell ya, and you really don't want to know.


    In school: We learn lessons, and are given tests.
    In life: We are given tests, and learn lessons.

  5. #5
    Boolit Grand Master Bazoo's Avatar
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    I’ve never used brass. But iron and aluminum both work well. I tend to like iron better. Partly because it holds temp so well. Partly because I don’t have to baby it like aluminum.

  6. #6
    Boolit Buddy
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    I still feel like a greenhorn when it comes to casting. I only have two iron molds but I do prefer them over my many aluminum ones. I’d love to try a nice brass mold. I should really buck up and get one ordered.

  7. #7
    Boolit Master
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    iron only for me. never had a Lee on my bench.

  8. #8
    Boolit Master
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    Iron, hands down. Most durable but also the most costly. Brass would come in second, then aluminum. Of course, I talking custom manufactures. Only own one Lee and it's for my ROA.

    Winelover

  9. #9
    Boolit Master
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    I've only used Iron & Alum molds for the last 50 years.
    They both work, I tend to gravitate towards aluminum molds and only 5 cav Accurate or NEI.

  10. #10
    Boolit Master


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    I have all three. The different metals all have their own traits, but that can be said of individual molds as well. It seems each mold has it's sweet spot. I try and take notes of temp and cadence when I get one running really good and put a slip of paper with it so the next time I use it I get good boolits faster. I tend to cast a lot at one time or over a couple of days, so it might go a year or more between using some of them.

  11. #11
    Boolit Grand Master


    Larry Gibson's Avatar
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    I have all three [currently have 87 moulds of single through six cavity] and only two of them are brass. I won't buy another brass mould as I've found aluminum or iron moulds to produce equal to or even better cast bullets without all the finickiness of the brass moulds.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

  12. #12
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    JonB_in_Glencoe's Avatar
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    What's the Best?
    (I always love it when questions are asked this way, it always leads to an entertaining thread)

    Myself, I prefer Aluminum molds for use with Ternary lead alloys.

    While I have a few aluminum Lee RB molds, I also have Iron RCBS and Lyman RB molds ...I prefer Iron molds when casting with pure Lead.
    ~~~~~~~~~~~~~~
    “If someone has a gun and is trying to kill you, it would be reasonable to shoot back with your own gun.”
    ― The Dalai Lama, Seattle Times, May 2001

  13. #13
    Boolit Master
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    I have all three materials and they all can make nice boolits without trouble. I do like the cast iron molds the best as these seem to have less quirks. I spray my vast iron down with Birchwood Casey Sheath after use and clean them off with brake cleaner before casting again. Hate to have them rust.
    "If everyone is thinking the same thing it means someone is not thinking"

    "A rat became the unit of currency"

  14. #14
    Boolit Mold
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    Iron for me. I store them in those protective sheets that use to come with Smith and Wesson handguns. Never had a rust issue.

  15. #15
    Boolit Master
    Mal Paso's Avatar
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    Quote Originally Posted by autogun View Post
    Iron for me. I store them in those protective sheets that use to come with Smith and Wesson handguns. Never had a rust issue.
    Excellent! A new excuse to buy more guns!
    Mal

    Mal Paso means Bad Pass, just so you know.

  16. #16
    Boolit Buddy Targa's Avatar
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    I won’t say one type is better than the other but my preference is aluminum.

  17. #17
    Boolit Grand Master GhostHawk's Avatar
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    I have one lyman 2 cavity round ball mold for .45 caliber rifle.

    Everything else is Lee and Aluminum. IMO the Lee 6 cavity's are the way to go.
    I truly believe we need to get back to basics.

    Get right with the Lord.
    Get back to the land.
    Get back to thinking like our forefathers thought.


    May the Lord bless you and keep you. May the Lord make His face to shine upon you and be gracious unto you
    and give you His peace. Let all of the earth – all of His creation – worship and praise His name! Make His
    praise glorious!

  18. #18
    Boolit Buddy
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    Do iron molds perform better straight out of the box?
    *
    I have three aluminum 5-cavity molds, one 2-cavity brass, and a single cavity iron. The iron mold is the only one I have not had to deburr & otherwise fix.

  19. #19
    Boolit Grand Master

    Winger Ed.'s Avatar
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    Quote Originally Posted by justindad View Post
    Do iron molds perform better straight out of the box?
    Actually, the few Lee molds I've had did better the first time I used them than the Iron molds.

    Iron ones do OK right out of the box, but seem to improve over time where you could open
    the handles and the boolits just fell out.

    I figure the Iron molds are sort of like Grandma's beloved old cast Iron frying pan.
    It also probably needed to be 'seasoned' when it was new.
    Never ask old people how they are doing.
    Because they'll tell ya, and you really don't want to know.


    In school: We learn lessons, and are given tests.
    In life: We are given tests, and learn lessons.

  20. #20
    Boolit Grand Master

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    I like iron but I have bought a few aluminum molds from Accurate lately.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check