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Thread: Questions about Casting Large Boolits

  1. #1
    Boolit Buddy
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    Questions about Casting Large Boolits

    I'm just started casting 710gr WFN for 500 S&W. I'm getting some small voids in the nose section and I think it's from pouring too slowly. The holes in the sprue cutter limit the speed I can pour.

    I'm a fairly experienced caster. Mold is preheated well, pot temp is 850F or a bit higher, fill out on the lube grooves is perfect. Alloy is 4% antimony 2% tin, balance lead.

    But there are swirl marks and some small voids in the nose section. I think I need to get alloy into the cavities faster. The bottleneck seems to be the size of the holes in the sprue cutter.

    Has anyone else experienced this? Has anyone enlarged the spue cutter holes? I'm thinking of trying that but now that I'm old and smart(?) thought I'd ask here first before I start drilling holes. Thanks in advance.

  2. #2
    Boolit Master

    rancher1913's Avatar
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    sure sounds more like a cold mold. I do 500 grain ones and to get good fill out and no swirls like you describe, I have to get the mold really hot.
    if you are ever being chased by a taxidermist, don't play dead

  3. #3
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    JonB_in_Glencoe's Avatar
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    Mold is preheated well
    there are swirl marks and some small voids in the nose section
    My first guess is that your mold isn't preheated well...but that's my guess.
    Are your boolits frosted?

    my 2˘
    I think there is a reason why many boolit casters use a Ladle to cast large boolits. I, myself, have never given ladle casting a good try, but I can say I've cast some large 50 cal pistol boolits (440gr and 550gr) and casting large boolits with a bottom pour pot is something I've found challenging. The mold needs to be preheated enough, but then the mold is easily overheated when pouring that much alloy into a mold. It takes practice to develop a slow rhythm, adding a small fan to blow on the mold during casting can help.
    Hope those few tips help.
    Good Luck.

  4. #4
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    I cast quite a lot of 500gr and 535gr for 45-70, and some .600" 530gr for Martinin Henry and haven't seen this issue before. The sprue is taking about 35 seconds to cool sufficiently with a fan which I think indicates a good mold temperature for a bullet this large, and pot temp is approaching 900F. In the past I've been able to solve these problems by going a higher temperature but not this time.

    Bullets aren't frosted or overly shiny, they look about right for this alloy.

    Has anyone enlarged sprue cutter holes for large volume bullets?

  5. #5
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    Never did any that heavy, but did make quite a few for a .480. The mold has to be good and hot, but you know that. I used to strive for frosted boolits, when they started to take a longer time to solidify I'd turn the heat down just a little and continue on.....
    Tom
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  6. #6
    Boolit Master Grmps's Avatar
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    If you are bottom pouring, hold the mold against the spout and see if that help.

    What mold manufacture is it? does it have adequate venting inside the mold?
    Sometimes you can use a fine diamond hone or sharpening stone and lightly east the top corners of the mold under the sprue plate to help with venting.

    As with any mold problem, the first thing I do is clean it again thoroughly, just in case I missed something the first time.

    The only time I have had to cast over 750° is casting buckshot in Lees 18 cavity mold.

  7. #7
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    JonB_in_Glencoe's Avatar
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    when you cast for for 45-70 and Martinin Henry, are you using that same alloy?

  8. #8
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    Quote Originally Posted by JonB_in_Glencoe View Post
    when you cast for for 45-70 and Martinin Henry, are you using that same alloy?
    yes for 500gr 45-70. Softer for the MH and Postell bullets.

  9. #9
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    Quote Originally Posted by Grmps View Post
    If you are bottom pouring, hold the mold against the spout and see if that help.

    What mold manufacture is it? does it have adequate venting inside the mold?
    Sometimes you can use a fine diamond hone or sharpening stone and lightly east the top corners of the mold under the sprue plate to help with venting.

    As with any mold problem, the first thing I do is clean it again thoroughly, just in case I missed something the first time.

    The only time I have had to cast over 750° is casting buckshot in Lees 18 cavity mold.
    Ladling. Accurate mold 3-cav. Cleaned well - scrubbed in boiling water and dish soap, rinsed in clean boiling water, and preheated well. I am fairly experienced, I cast about 50,000 bullets a year and sell them.

    I've heard of some casters having a similar problem and needing to enlarge the nozzle on the ladle to get a faster pour in large volume bullets.

    Poor mold venting could be the issue all right. I'll give it another scrub and use a hardened scribe to softly clean the vent lines.

  10. #10
    Boolit Bub
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    Quote Originally Posted by jethunter View Post
    I'm just started casting 710gr WFN for 500 S&W. I'm getting some small voids in the nose section and I think it's from pouring too slowly. The holes in the sprue cutter limit the speed I can pour.

    I'm a fairly experienced caster. Mold is preheated well, pot temp is 850F or a bit higher, fill out on the lube grooves is perfect. Alloy is 4% antimony 2% tin, balance lead.

    But there are swirl marks and some small voids in the nose section. I think I need to get alloy into the cavities faster. The bottleneck seems to be the size of the holes in the sprue cutter.

    Has anyone else experienced this? Has anyone enlarged the spue cutter holes? I'm thinking of trying that but now that I'm old and smart(?) thought I'd ask here first before I start drilling holes. Thanks in advance.
    I'm certain that you are getting very sage advice from these other fellas, but thought I would add that I had the same issue casting for a 500/465. I would get absolutely beautiful bullets, sharp grooves, clean edges - until you looked at the nose. Swirls on nearly every one, cross sectioning revealed cavities. Someone else from this forum recommended that I immerse my mold base in my pot while pouring. Voila'!! Perfection. The mold was far more massive than any others I had used before and was not heating uniformly. Also, using a torch cleaning file, and making sure your ladle spout is large enough also helped.
    Good luck!

    Sent from my HTC6545LVW using Tapatalk

  11. #11
    Boolit Buddy MOA's Avatar
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    The big downside to enlarged sprue holes is when you go to cut it the greater amount of lead now created by the enlargement will be harder and more force needed. I had to open up two Lee .515 molds and now can only cut the sprue with a protected headed hammer.

  12. #12
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    What I found with bigger boolits is that you cast a few in quick fashion and toss 'em back to heat up the mold (in addition to the hot plate).
    That heats the innerds of the mold. Then you quickly pour lead into each cavity. And then you whistle a little while you watch the sprue cool and then give a little while to let it kind of gel in the mold.
    What I found is that the bigger the boolit, the slower the process. I've got some 80 grn 30s that you have to cast fast to keep a good fill out. Then I've got a mold the makes 240 grn .430s that you slow down for. Then my 400 grn HP mold for my 45 is even slower. It just takes time to heat up the mold and also takes time to cool it down...

  13. #13
    Boolit Master Grmps's Avatar
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    This may be a dumb idea but, try tilting the mold when you start pouring, see if that improves the fill at the tip. I know with the bottom pour sometime where/how the flow of the lead enters the sprue hole makes a difference.

    If you decide to enlarge the sprue hole, don't do it on the mold and make sure you smooth/polish the bottom well.

  14. #14
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    Quote Originally Posted by MOA View Post
    The big downside to enlarged sprue holes is when you go to cut it the greater amount of lead now created by the enlargement will be harder and more force needed. I had to open up two Lee .515 molds and now can only cut the sprue with a protected headed hammer.
    Good point and makes sense. I didn't consider that.

  15. #15
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    Mine did the same with 440 gr for the 500. Once mold got hot enough, no more veins and filled wonderfully.

    “To achieve victory we must mass our forces at the hub of all power and movement. The enemy’s "center of gravity”

    ― Karl Von Clausewitz

  16. #16
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    Quote Originally Posted by Grmps View Post
    This may be a dumb idea but, try tilting the mold when you start pouring, see if that improves the fill at the tip. I know with the bottom pour sometime where/how the flow of the lead enters the sprue hole makes a difference.

    If you decide to enlarge the sprue hole, don't do it on the mold and make sure you smooth/polish the bottom well.
    Quote Originally Posted by Dieselhorses View Post
    Mine did the same with 440 gr for the 500. Once mold got hot enough, no more veins and filled wonderfully.
    Quote Originally Posted by 44Blam View Post
    What I found with bigger boolits is that you cast a few in quick fashion and toss 'em back to heat up the mold (in addition to the hot plate).
    That heats the innerds of the mold. Then you quickly pour lead into each cavity. And then you whistle a little while you watch the sprue cool and then give a little while to let it kind of gel in the mold.
    What I found is that the bigger the boolit, the slower the process. I've got some 80 grn 30s that you have to cast fast to keep a good fill out. Then I've got a mold the makes 240 grn .430s that you slow down for. Then my 400 grn HP mold for my 45 is even slower. It just takes time to heat up the mold and also takes time to cool it down...
    Good points, mirror my experience when I started casting 535 postell and 500 gr WFN 45-70 bullets. I'm getting good fill with sharp edges on the grooves in the 700gr bullets. The swirl marks don't bother me, they tend to fade away when the bullet ages a bit but there are some small voids if you look closely and that's what I'm fighting against right now. I've cleaned the mold again and will try it tomorrow . Won't enlarge the sprue cutter holes just yet.

  17. #17
    Can you post a picture of the cavity?
    I’m wondering if there is just very little mass to the mold near the nose end of the block. A thin wall here could cause rapid cooling and give you fits.

  18. #18
    Boolit Bub
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    I have cast a lot of large boolits in both pure lead and alloy's. Ladle casting is tough on long boolits. I drilled the spout of an RCBS ladle to allow the lead more head pressure and volume out of the ladle. Pressure casting also worked good. The best way I have found is, I got one of the new Lyman bottom pour and get the mold real close to the spout and open up the flow control. Head pressure and speed/volume going into mold seems to work the best for me. Like was said before, make sure the mold is venting. If I had to do it with the ladle I would pressure cast.
    Tony

  19. #19
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    Quote Originally Posted by Michael J. Spangler View Post
    Can you post a picture of the cavity?
    I’m wondering if there is just very little mass to the mold near the nose end of the block. A thin wall here could cause rapid cooling and give you fits.
    I think you have something there, the cavity wall between the end of the nose and the outside of the mold is very thin.

    Quote Originally Posted by ABJ View Post
    I have cast a lot of large boolits in both pure lead and alloy's. Ladle casting is tough on long boolits. I drilled the spout of an RCBS ladle to allow the lead more head pressure and volume out of the ladle. Pressure casting also worked good. The best way I have found is, I got one of the new Lyman bottom pour and get the mold real close to the spout and open up the flow control. Head pressure and speed/volume going into mold seems to work the best for me. Like was said before, make sure the mold is venting. If I had to do it with the ladle I would pressure cast.
    Tony
    I cleaned the mold again and it was venting better today, also raised pot temp up to 900F. Still some bullets with small voids but most were good. I think I can improve my pouring technique and get 100%.

    Thanks to everyone.

  20. #20
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    A friend of mine lightly taps the mold (500gr 45-70) as soon as the puddle forms on the sprue plate, claims it knocks out any bubbles in cavity. I have no idea if this is a common practice or if it even works. When I cast that size I don't get enough of a weight variation to make me think I have any air trapped in the boolits.
    Warning: I know Judo. If you force me to prove it I'll shoot you.

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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
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LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
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