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Thread: The MP 432-250 / H&G 503

  1. #1
    Boolit Bub Bongo Boy's Avatar
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    The MP 432-250 / H&G 503

    I have finally started pouring lead into this mold as of this evening, and had some real challenges.
    I started with the penta plug and getting the bullets to drop was a real frustration. Not owning a rawhide mallet and not wanting to use a hammer handle, I eventually extracted the real problem bullets with the pliers. Needless to say, those all had to go back in the pot.

    I let the mold cool down and turned the hollow point plugs around hoping a flat nose would help get things going, but almost no help there, either. Absolutely impossible to get 1 of the 4 to come out no matter what I did, until I finally took a hammer handle and beat the tar out of the thing.

    So now I think I appreciate why Lyman, as I understand it, modified the Keith original design from fairly square-bottom grease groove to a larger radius design.





    Anyway, just wanted to share my rather miserable experience. Tomorrow I think I pick up a rawhide mallet. This will be the first mold I have had from any maker (including MP hp molds) that causes this much fuss. I'm thinking old Elmer maybe never actually had to cast his own designs, just shoot them. They're going to be beautiful bullets once I get the mold running right, but for now it takes so long to get them out the mold cools down enough I can barely crack the sprue plate open.

    These I'm seating right a 1.675" OAL--can't waits to shoot 'em.
    Last edited by Bongo Boy; 03-29-2015 at 03:12 AM.
    If I had to live my life again, I'd make the same mistakes, only sooner. T Bankhead

  2. #2
    Boolit Grand Master

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    You should never have to "beat the tar" out of a mould.

    My suspicion is that you did not pre-heat the mould and it was too cold to cast with. You will get stickers if the mould is too cool.

    I will agree that Miha's penta pins can be an issue but again, if the mould and pins are pre-heated and kept hot you should not experience serious stickers. Yes, you may have to tap the mould handle pivot. You should never hit the mould blocks themselves.

    I use an old hammer handle or wooden dowel to tap the the mould handle pivot to shake the blocks to get boolits to drop and it should not take a pounding, just a tap or two.

    Once you pre-heat the moult then casting should go well. The Cramer style moulds do take a bit of getting used to though and brass moulds require a hotter than "normal" melt along with rapid casting to keep the mould hot. That is the key... keep the mould hot. The sprue puddle should take a few seconds to freeze and should not be solid hard when you cut it.

    It is possible that there are some burrs though Mihec moulds in my experience are pretty much "perfect". In any case, if you run a Q-tip around the edges of the cavities you should find any burrs... or use a big magnifying glass to examine the mould blocks. If there is anything wrong I am sure Miha will fix it.

    By the way, I have the same mould form the original run and it is a beauty.

    It sounds like you have several other moulds and this one is the only problems. If so that may be the brass issue. Cast hot and keep it hot! Also, some have reported "tinning" of brass moulds. I normally do not add tin and have had no problems that way but it wouldn't hurt to check the mould cavities to see if there are tin deposits. If the brass is clean and the melt hot with tin in it then it is a possibility. If there are tin deposits then you are soldering boolits to the mould. You will have to heat up the mould to wipe off the deposits then likely put an artificial patina on the mould by heat cycling or coating the surface with something to lightly oxidize it. There are a couple of threads on adding a patina to brass moulds if you search.

    Hopefully there is something there that helps.

    Longbow

  3. #3
    Boolit Master
    Mal Paso's Avatar
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    Longbow covered it, I posted this elswhere this morning:

    Iron molds hold heat and aluminum molds don't need much heat. Brass molds are harder to get up to temp because they have a similar mass as Iron but conduct and dissipate heat much faster.

    I own both the 503 HP clone and 432640 HP. I preheat on a hotplate with a steel plate over the coils to just below casting temperature. Make sure the 2 pins attaching the handles aren't sticking out below the mold so the bottom of the mold and the HP pins contact the plate. After you get the mold up to temperature consistent pours will keep it there. If something breaks your rhythm the mold can go back on the hotplate.
    Mal

    Mal Paso means Bad Pass, just so you know.

  4. #4
    Boolit Bub Bongo Boy's Avatar
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    Thanks guys. The mold is definitely up to temperature and the bullets looking very good. I don't preheat with a hotplate but use a torch (and a lot of motion, of course, to avoid unevenly or over-heating anywhere).
    I do sometimes suffer a bit of tinning on both aluminum and brass molds, but the only issue that has ever caused is keeping the blocks from closing completely, and I check for that before nearly every pour by inspecting against a bright light. It's always come from running just a bit too hot, I think, or losing cadence and accidentally dropping a sprue into the pot with the mold over the pot. Judicious use of a new razor blade has always removed anything a glove wouldn't.

    We'll give the blocks a very thorough inspection today with the Opti-Visor on, looking for any burrs or other issues--but I've never seen anything but the nicest and most-complete finishing on all the molds I have, including MP, Accurate and Lee. Never had to 'clean up' any of them right out of the box.

    I did go over this mold with acetone and a Q-tip to remove any oil, and I've never done that with any mold before. Maybe I got it too clean.

    In any case, we'll figure it out and get it running--I'm very confident there's nothing 'wrong' with the mold, but it sure has presented a challenge I've never had before.
    If I had to live my life again, I'd make the same mistakes, only sooner. T Bankhead

  5. #5
    Boolit Master
    Mal Paso's Avatar
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    I'm right handed. I set up the mold with sprue plate pivot near the handle, opening to the left and the sliding pins entering the left side. After cutting the sprues I turn the mold over, open it and gently push the pins (now on the right side) in with my rawhide mallet. If the boolits don't fall off a tap on the handle does it.
    Mal

    Mal Paso means Bad Pass, just so you know.

  6. #6
    Boolit Master dkf's Avatar
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    Mold was not hot enough most likely. All my MP brass molds needs the higher mold temp to drop freely. I found I have to run the lead temp hotter than all my aluminum molds too.

  7. #7
    Boolit Bub Bongo Boy's Avatar
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    Quote Originally Posted by dkf View Post
    I found I have to run the lead temp hotter than all my aluminum molds too.
    Ah! I was running at about 735F and thought "okay, close enough". But I do normally run much closer to 760 or even more, when I'm paying attention. Funny thing is that the last 10,000 bullets I've cast have either been with Accurate or MP brass molds, with no problems. Maybe that temp difference is enough, and maybe I didn't check it often enough as the evening wore on.
    Last edited by Bongo Boy; 03-29-2015 at 11:52 PM.
    If I had to live my life again, I'd make the same mistakes, only sooner. T Bankhead

  8. #8
    Boolit Master dkf's Avatar
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    Aluminum actually suits my speedy casting style better but the MP molds are such well made purty molds I keep buying them. What I also like about the aluminum is it seems I can run my melt temp a good bit cooler and still get good fill out and shiny bullet that release easier. I like brass but I sure would buy MP molds in aluminum if he made more of them.

  9. #9
    Boolit Bub Bongo Boy's Avatar
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    Thanks for the tips. Just ran a test batch and they're beautiful, and I'm able to easily drop all 4 with one or two taps to the tongs. Works great. I did take my eye off the ball for about 15 min and the pot temp was about 815-830F, but things were looking fine--not even a frosty bullet. I backed 'er off a little (I use propane, currently), and they continued to come out of the mold just fine.

    Honestly, I'm so simple sometimes and I have to admit--tapping the tong pivot never occurred to me. Happy, happy, happy.
    Last edited by Bongo Boy; 03-29-2015 at 11:53 PM.
    If I had to live my life again, I'd make the same mistakes, only sooner. T Bankhead

  10. #10
    Boolit Master dkf's Avatar
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    Are you using a Lee pot? I use a 20lb Lee and I need to find the time to put a PID on it. It does not hold a specific temp very well, even casting small .22 bullets.

  11. #11
    Boolit Bub Bongo Boy's Avatar
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    No, I'm running what I think is a 9 quart iron Dutch oven, sitting over a 5" diameter ring burner/venturi type thing that looks like it may have been a burner off a commercial gas range or something. Once the pot is melted and up to temperature, I just adjust the gas cock it by tapping with a wrench--and go by sound. I can control the temp to about +/- 10F I'd say, if I work at it. They key is that it probably holds 50 lbs of lead half-full, so dropping an ice cold 1/2 lb ingot in I don't think does a whole lot to the temperature, at least not for very long.

    I'm sketching out a PID-controlled melter, but it looks like one of those 'projects' I'd never finish. I'd like a floor-standing cabinet with mold storage down below, the pot under a ventilated hood up above, cooling slot for the mold, etc., and the ability to crank down industrial casters to allow moving the whole unit when not in use. It'll never happen!

    One from tonight after hitting the sizer:



    The cavernous crimp groove on this design just cracks me up--for the man who likes a serious crimp.
    Last edited by Bongo Boy; 03-29-2015 at 11:58 PM.
    If I had to live my life again, I'd make the same mistakes, only sooner. T Bankhead

  12. #12
    Boolit Master




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    Nice sharp edges, Bongo. Good work. You must have some tin in there.
    Politicians are a lot like diapers. They should be changed frequently, and for the same reason. Benjamin Franklin

  13. #13
    Boolit Master
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    WHOOOOOEEEE! Bongo, that's a nice looking bullet. You did good. Glad you got her running.

  14. #14
    Boolit Grand Master
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    I have the same mold seems that after you cast with it for awhile
    you'll become more consistent with your boolits
    yes the square lube groove is and can be a pain the pentas once smoothed out will work well
    keep at it
    Hit em'hard
    hit em'often

  15. #15
    Boolit Master curioushooter's Avatar
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    These are a few things that can be helpful with brass HP molds that I've learned:

    1 Clean the heck out of it. When you get the new mold scrub it with hot tap water and dishsoap and a tooth brush. Take apart the whole thing and let it dry.
    2 Hit the thing with some good quality brake cleaner that leaves NO reside.
    3 Immediately put all the steel parts into a plastic bag with VCI paper. Use surgical gloves to assemble the cramer pins. Screw the guide pins in all the way and just slightly back them off. Put them in the mold and put the smallest dab of included lubricant on the pin from the OUTSIDE of the mold using a toothpick. A drop is about 10x more than you need. Lube the SPRUE PLATE by wiping with a perfectly clean cotton cloth with about one drop of lubricant on it. NO MORE. DO NOT PUT LUBE on the blocks other than the alignment pins. JUST A DAB. Lube the pin that holds the plate on with the same cloth that you used to lube the sprue.
    4 Heat cycle the brass blocks in an oven about a 4 times at least. Bring them up to temp. Then let them cool in the air.
    5 First casting session expect it to suck
    6 It will get better
    7 If you use a good clean alloy, well fluxed, about 800 degrees, and preheat the mold and run it as fast as you can you will cast the most beautiful bullets there are
    8 unfotunately the binary alloys that work best with HPs are shrink the least, making them the most sticky in the mold. lead and tin also like to stick to brass (they are basically solder) so don't overheat the alloy (over 900 degrees and you can do damage).
    9 if you have a lee pot strive to keep air from blowing it because their thermostats suck and can easily overheat check with a thermometer frequently
    10 have good quality needle-nose pliers handy, especially with the penta points

    Anyone cast solids with this HP mold? My solid pins in the 358429 clone and the 359 Hammer result in an imperfect nose with a slight seam. Are the larger bore ones this way (or does the pin take the full diameter of the nose?).
    Last edited by curioushooter; 02-11-2020 at 03:25 PM.

  16. #16
    Boolit Buddy
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    Strangely I didn't have any issues with pentas but I did coat them with pencil lead first. That and the pins were HOT. I do prefer the large HP pin better and the bullets come off most easily.

  17. #17
    Boolit Master curioushooter's Avatar
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    I heard of that pencil lead trick only recently; haven't tried it yet. Seems like a good idea though!

  18. #18
    Boolit Master

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    Glad you got it straightened out......
    JMHO-YMMV
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    dgilbert07 at windstream dot net

  19. #19
    Boolit Master
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    A few heat cycles really help with a new MP brass hp mold, after an ultra careful cleanup.

    I do four cycles using a hot plate. Then I may cast 15 min and let the mold cool. Another 15 min later, maybe third. It takes half a day to break it in but it's worth it. The following day bullets are raining,I cast 357,44,458 and 500 with penta pins. No tricks,a clean hot mold.

    These molds are so good,casting is almost boring now.

    I think I need this mold...

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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