Oversized cast boolits

[Microgun]

This morning I cast almost a thousand 357 Magnum semi wad-cutters. I tried to run them through my resizing die and almost broke the handle on my RCBS Rock chucker. The mold is a Lee 6 cavity 158 grain semi wadcutter. Why would the bullets come out of the mold at .365 - .372 diameter. After running them through the sizing die it completely wiped off the ribs on the side of the bullet making a solid slug that was pretty damn ugly

[Dusty Bannister]

Probably the most common issue is how you hold the mold handles. The third handle, the one that cuts the sprue, should not be gripped along with the other two because it will force the blocks apart and result in fins and oversized bullets. I this what you were doing?

[rbuck351]

One of three things, either the mold was cut wrong, stamped wrong or you are not getting the mold closed all the way (they will be out of round). If they are varying that much in diameter, it sounds like the mold is not closing well.

Check for dings on the parting line edges of the mold or a bit of lead stuck on the parting line faces that may be holding the mold halves apart.

[Conditor22]

Check and see if the boolits are round (out of round) If so then you are holding the sprue handle and not letting the mold close completely.

Are all the boolits this big? Or do you have some that size easily?

[Larry Gibson]

Probably the most common issue is how you hold the mold handles. The third handle, the one that cuts the sprue, should not be gripped along with the other two because it will force the blocks apart and result in fins and oversized bullets. I this what you were doing?

What he said......don't ask how I know.......

[charlie b]

What he said......don't ask how I know.......

Yeah, I found out how that works too :)

[Conditor22]

Yeah, I found out how that works too :)

The first time I did that I had lead pouring out the bottom of the mold --- that was disconcerting [smilie=b:

[Microgun]

I'm holding the mold by the ends of the handles and I actually went back and re-poured some more heads to make sure I was doing it correctly. I mic'ed the mold and it comes up at 358 but the bullets are coming out 362 how is this possible.

[FLINTNFIRE]

Hold the mold blocks up to the light and make sure they are tight and no light shows through , if it does check for splatters of lead , burrs or alignment pins , if it has no light showing through and you are holding molds right and they are tight then double check your measurements and cast and check your bullets , are they round or are they out of round ?

[Conditor22]

I'm holding the mold by the ends of the handles and I actually went back and re-poured some more heads to make sure I was doing it correctly. I mic'ed the mold and it comes up at 358 but the bullets are coming out 362 how is this possible.

If you are using harder alloy than the mold was made for you could get a much bigger boolits. I usually cast mine around 10 BHN

harder alloy drop bigger/lighter

[Microgun]

99.99% pure lead

[Microgun]

I don't understand how the alloy or the hardness has anything to do with it. the mold is what the mold is if it's 358 it should cast bullets at 358 can they possibly grow after I open the mold

[mroliver77]

Did you check to see if they are round or or oval? Measure at parting line and then 90 degrees from that. Check all six and see if'n the middle cavities are dropping larger. Did you check to see if light can be seen between cavities are closed?

[FLINTNFIRE]

Shrinkage , all molds are cut for a alloy , so harder shrinks less then pure , and then mold temperature makes a difference also . If I remember correct . I buy molds for range lead and or wheel weight alloy , black powder molds and slugs are usually cut for pure lead .

Heat mold to same temp. on a hot plate and try to keep alloy the same .

[Dusty Bannister]

I'm holding the mold by the ends of the handles and I actually went back and re-poured some more heads to make sure I was doing it correctly. I mic'ed the mold and it comes up at 358 but the bullets are coming out 362 how is this possible.

This is usually the result of not confirming that the mold blocks are completely closed and no light is seen between the mold blocks. The Lee 6 cavity mold can be a problem if not held correctly. The blocks must be held closed with the mold handles. The sprue cutting handle must be in the correct position so the the plate is in the fully closed postion and slides under the hold down bolt. BUT IT MUST NOT BE GRIPPED with the other two handles or the lever will cam the blocks apart at the handle hinge end of the blocks. You will not see this because the sprue plate covers this gap. Even slight pressure on the sprue cutter handle can create this problem. You will also see this as the bullets at one end of the blocks being nearly normal, and those from the other end of the blocks, oversized and often with fins. It is helpful in determining the problem if you will answer the questions being asked.

Alloys containing antimony do not shrink as much as pure lead bullets when cool so yes, the alloy does make a difference in the final cast bullet.

[ABJ]

I don't understand how the alloy or the hardness has anything to do with it. the mold is what the mold is if it's 358 it should cast bullets at 358 can they possibly grow after I open the mold

Pure lead has the most shrinkage.
Lee molds have the largest tolerance window of any mold mfg currently producing molds. It is not uncommon for a Lee 358 to throw a .361. I have two that do that. If you close the block and hold the two handles, then close the sprue cutter you can feel the mold blocks open when close to closed all the way. Back off on the sprue cutter when you feel that happen.
One other thing to look at is the face of the blocks might be a little proud where they come together. A fine stone at about 45 degrees will fix this if it is there. I have had to do this to several 6 cavity but none of my two cavity's have had this problem.
Tony

[Hossfly]

I’ve had that happen at first, starting with casting, fins and out of round boolits. Stopped casting and find out what is wrong. Held up to light and rotate, looking for any light passing thru. Found it, wasn’t obvious, cleaned and reset guide pins, don’t know what was holding open but it cleared up after that episode. Started being careful about how tight to hold handles, and didn’t think about the sprue handle. Good luck, don’t give up, mistakes just get remelted.

[Soundguy]

I don't understand how the alloy or the hardness has anything to do with it. the mold is what the mold is if it's 358 it should cast bullets at 358 can they possibly grow after I open the mold

harder alloys make bigger bullets..

[onelight]

It's not the alloy with the size difference Microgun is getting :)

[Soundguy]

It's not the alloy with the size difference Microgun is getting :)

No duh!

But.. he said he didn't understand how alloy had any impact on bullet size and it does

[dtknowles]

I don't understand how the alloy or the hardness has anything to do with it. the mold is what the mold is if it's 358 it should cast bullets at 358 can they possibly grow after I open the mold

You measured the mold while it was cold. It gets bigger when it is hot. Lead and aluminum don't have the same coefficient of thermal expansion and each alloy has a different casting temperature and coefficient of thermal expansion.

They don't get bigger after you open the mold, they shrink but some more than others.

Tim

[waksupi]

You may need to tap the alignment pins in a bit.

[Conditor22]

Pictures would be helpful

[Dusty Bannister]

Yes, with the bullets from a variety of angles in one photo and the mold as it is held when filling from the pot.

[Microgun]

Thanks for all the responses. I will check for a gap between the two halves. I'm almost positive that I poured a bunch of times when the sprew plate was not 100% under the holding Bolt

[Microgun]

I believe there's also an issue with the swaging die it was very hard going through that die. I thought I was going to break the handle off of my rock chucker press. in fact I ran a few 9 mm heads through the 357 swaging die and it wiped the lube grooves completely off on the 9 mm, it should not have hardly touched those

[Microgun]

Okay so I took the mold apart I cleaned it up I found two very small pieces of lead in between the two halves but beyond that there is almost .003 of an inch Gap in between the two halves of the mold. Is there any way to remove the alignment pins from the mold so I can Mill each side down enough to mate them correctly

[Microgun]

So of the factory available molds like Lee, Lyman, RCBS, Seaco. without going to a custom mold what would be the best quality in order from best to worst

[Dusty Bannister]

Okay so I took the mold apart I cleaned it up I found two very small pieces of lead in between the two halves.

This can create a gap that would produce oversized or out of round cast bullets/boolits.

There is almost .003 of an inch Gap in between the two halves of the mold.

Are the two mold halves held apart by one or both of the alignment pins extending out too far from the mold block? Generally, these aluminum molds do best when heat cycled several times before putting them into production casting bullets. If the pins are actually holding the blocks apart, sometimes warming the mold blocks and then with the mold half on a flat piece of wood, tap the pin with a brass hammer until the blocks can fully close. Milling the mold half is probably not needed.

Is there any way to remove the alignment pins from the mold so I can Mill each side down enough to mate them correctly

Why be concerned about that until you prove that the blocks are not correctly fit when fully closed?

[Mitch]

Is the mold warped as in gap in the middle and touching on the ends?

[popper]

Make sure the (female) pins have no junk on them. Mould lube will coat them. As it's a lee mould, lightly tap the pin in. Tap, measure, repeat as needed. Also check around the pins for Al flash. Use GOOD straight edge to verify mould face flatness. You don't mill the face. Place on flat plate and oily valve compound. Same with sprue plate if needed. IHHO, 3 thous. isn't the problem, you are talking 10. I use Accurate but NOE is good, cost is reasonable but get a 4 hole mould. I only use 2 hole for rifle - more consistent results. And just as fast as my (long gone) 30/30 6x Lee. If you bought from Lee (midway, etc) and the mould is bad, send it back!
For pure Pb, pot temp should by 650F or so. Hotter takes awhile to cool but also heats up the mould more and bullets are slightly bigger - holes expand.
If using Lee sizer, verify the sized bullet OD. Pure comes out much smaller, no 'spring back'. Out of 7, 2 are as marked.

[Mk42gunner]

Check the area around the alignment pins for swelling. I have one of the group buy molds from years ago did almost exactly what yours is doing. It about drove me nuts figuring out what the problem was. I guess the pilot hole for the alignment pins was either unlubed or undersized when they were driven in.

I trimmed the area around mine with a knife (not very neatly, but by then I was ready to throw it in the trash) and reset the pins, good mold ever since.

Robert

[Conditor22]

Okay so I took the mold apart I cleaned it up I found two very small pieces of lead in between the two halves but beyond that there is almost .003 of an inch Gap in between the two halves of the mold. Is there any way to remove the alignment pins from the mold so I can Mill each side down enough to mate them correctly

Again a picture of the gap would be very helpful

the alignment pins can be tapped in or out as needed. I have been known to put the mold in a vise (no handles) and clamp it together often moving long w=allignment pins a little.

IF the mold (not just the alignment pins) are toughing on both ends and there is a gap in the middle -- unfortunately somehow the mold got warped, I know of no simple fix.

sanding the face until the warp is gone will give you different sized/out of round cavities, the center ones will be bigger and rounder while the ones on the ends smaller and more oval in shape.

yes you could cast some hard boolits out of the middle cavities and polish the outer cavities until they are the same size again ---- a lot of work.