Preventing voids in bullets, an experiment.

[Maillemaker]

So I was playing with my new Lyman Parker Hale mold, which has a very truncated cone for making the hollow base. Most of my molds come to a rather sharp point for core pin.

I wondered if this mold would be less prone to making voids because of the lack of a point on the core pin. Most of my minnies, when they make voids, make them at the cusp of the core pin.

I theorized that perhaps the voids are initiated in the bullets much like bubbles are in a beer or glass of soda - they initiate on tiny microscopic defects in the glass. I theorized that perhaps voids were initiating in a similar manner, the apex of the core pin being a great place to initiate a "bubble".

I noticed right away that the Parker Hale mold, with its flat-top core pin, seemed to be less prone to voids. But there were, on occasion, perhaps 5 out of 20 drops, voids forming on the top of the core pin. The top of my core pin was fairly smooth, but you could still make out concentric circles of the tool marks left on it from manufacture.

Could this rough surface be initiating voids?

To test this idea, I took my core pin and polished the top face of it until it was nearly mirror bright.

And lo and behold, it definitely made a difference. Instead of 5 out of 20 having a void, now perhaps 1 in 20 had a void, or less.

Now I still did get the occasional void, and I do not know why, but I tend to think that defects in the mold may be propagation points for voids.

The next thing I need to fix is that these PH bullets have such thin skirts that they are easily dented when they drop into my bucket of water. I've got to find a new way of cushioning the bullets when they drop from the mold.

Steve

[Hickok]

Maillemaker, my P-H mould does the same thing at the core pin. Sometimes it looks like small blisters or tiny puddles at the flat of the hollow cavity. I will have to try your fix.

I drop my bullets on an old pillow coverered with rags. works good for me, and bullets don't get dented.

I do drop some wheel weight bullets into water to harden them when cast for my .44 magnum. As you probably already know, beware that no water splashes aroundd your lead pot.

Try this to help keep your bullets from getting dented. Soak a sponge in water, and let it float in your water bucket. drop your bullets on the sponge. They will set on the sponge for a second, and then tip it over and gently fall to the bottom.

[Maillemaker]

What I currently do is I have a shop towel clamped to the bucket mouth, making a funnel down to the water. There is a small slit in the towel to let the bullet fall down into the bucket.

The towel prevents splashing, and it slows the bullet down so that it rolls down into the water.

The problem is, I think, that after it falls from the towel (or your sponge), that it then plumets the rest of the way to the bottom of the bucket, where it hits other bullets and dents them or itself.

When you drop onto a pillow or pile of rags, how do you keep them from hitting each other? You can't pick up previous bullets, as they will still be very hot. Unless you wear gloves I guess?

Steve

[Hickok]

As I drop bullets I drop them all around on the pillow. I put old towels on the pillow. When I start getting a pretty good spread of bullets, I lift up one end of the towel and gently and slowly ease the bullets off onto another soft pile of cloth or towels I have laid beside the pillow. Spread the empty towel back on the pillow and start casting again. Kinda like I am handling Nitro!

I use cotton fabric, no polyester or junk that will melt to the bullets. Old tee shirts work good too. The towels and the pillow get brown tattoos from the bullets, so don't use any of the wife's good items. Ask me the question, "How did that turn out?" "No too good!";)

I wear a leather welding glove on the hand that holds the mold, and just a regular leather work glove on the other hand. Usually when my mold starts getting too hot is when I take a break and move the bullets off the pillow. Cools the mold a little.

I really have to watch when opening the molds and dropping the bullet, as I can ding a minie by having it it the opposite side of the mold block.

[Mike Stein]

I cant the mold during the initial pour and that seems to significantly reduce voids. I'll have to polish the base pin as you've tried and see what it does.

[Maillemaker]

I also canted the mold usually, but twith the Parker Hale mold the inlet is so small it's hard to get the lead to go down the hole when you cant the mold. Plus with the big honking KNOB on the bottom of the mold that Lyman uses its hard to have enough room under my bottom-pour pot to get into a good position other than a straight-in drop.

Steve

[Mike Stein]

What kettle are you using. Mines the RCBS.

[R. McAuley 3014V]

If you are using a bottom pour ladle, you might find casting a little easier by switching over to using a table spoon to reduce the amount of molten lead per ladle, and you may find that enlarging the vent hole on the mould will allow for more air to escape from the mold as you are filling the mold cavity with molten lead. You should find that when the lead is the right heat (temperature), air bubbles or voids as well as wrinkles will no longer occur, and at that temperature, it may take about a "four-count" (one thousand one, one thousand two...and so forth) before the lead solidifies after being poured into the mold. If you use a mold prep like the graphite type, you might also try "smutting" the inside of the mold cavity with a candle flame will further eliminate not only "wrinkling" but will improve the mold release time. On average, I cast about 250 minies per hour using a table spoon and dipping the lead directly from a 10-pound lead pot at a temp of about 950 deg. I tried using a Lee production pot but went back to what I found worked best, and I have been using this method for 40 years.

[Hickok]

Richard I did the same as you. I bought an electric bottom pour melting pot and just didn't like it. Went back to my old Coleman stove, a pot, and my laddle. The only upgrade I have made in 40 years is I hooked up propane to the Coleman stove.

[Eggman]

I jammed a nail in the bottom spout of the Lee pot and bought a Dixie ladle for dipping out of the top which does a beautiful controlled pour. By using the Lee pot you can regulate the lead temperature. I never liked working above an open flame.
Be sure to unscrew the pot lever assembly from the top first.

[Maillemaker]

I've never used anything but my bottom pour Lee pot, but I love it. By pouring off the bottom you don't have to worry about dross in your bullets. And you get a nice controlled pour every time. I like it.

Steve

[jonk]

I used to get about 50% rejects for otherwise good bullets due to voids at the top of the core pin; I look foward to trying this.

Part of the problem was, the sprue solidifies before the heavy core of the bullet does; I've found it to help things considerably to keep the mold hard pressed up against the spout on my 20 lb bottom pour pot, adjusted to really let the lead flow; then pull the mold away after 5 sec or so and let the sprue puddle and harden. Now I'm down to about 15% rejects, but would love to improve that further.

I always read about folks saying 'oh, gotta ladle pour the minies'... personally I never had any luck with ladle pouring minies whatsoever, with about 75% rejects. I DO still ladle pour my sharps bullets as I have 3 pots- big one is pure lead, medium is wheeleights for smoothbores and smokless, small one is 1/3 ww to 2/3 pure for the sharps pretty much only.

But, whatever works for you.

[Michael T.]

So I was playing with my new Lyman Parker Hale mold, which has a very truncated cone for making the hollow base. Most of my molds come to a rather sharp point for core pin.

I wondered if this mold would be less prone to making voids because of the lack of a point on the core pin. Most of my minnies, when they make voids, make them at the cusp of the core pin.

I theorized that perhaps the voids are initiated in the bullets much like bubbles are in a beer or glass of soda - they initiate on tiny microscopic defects in the glass. I theorized that perhaps voids were initiating in a similar manner, the apex of the core pin being a great place to initiate a "bubble".

I noticed right away that the Parker Hale mold, with its flat-top core pin, seemed to be less prone to voids. But there were, on occasion, perhaps 5 out of 20 drops, voids forming on the top of the core pin. The top of my core pin was fairly smooth, but you could still make out concentric circles of the tool marks left on it from manufacture.

Could this rough surface be initiating voids?

To test this idea, I took my core pin and polished the top face of it until it was nearly mirror bright.

And lo and behold, it definitely made a difference. Instead of 5 out of 20 having a void, now perhaps 1 in 20 had a void, or less.

Now I still did get the occasional void, and I do not know why, but I tend to think that defects in the mold may be propagation points for voids.

The next thing I need to fix is that these PH bullets have such thin skirts that they are easily dented when they drop into my bucket of water. I've got to find a new way of cushioning the bullets when they drop from the mold.

SteveWhat did you use to polish your core pin?

[Maillemaker]

I started out with some diamond paddle files.

But in the end I found it easier to maintain a good, flat alignment with some fine sandpaper on a rubber sanding block and a few drops of oil. I only polished the face of the pin. The Parker Hale mold pin is not pointy like most minnie core pins, it has been cut short and flat to increase the weight of the bullet.

To polish a regular core pin you'd have to chuck it up in a drill somehow.

Steve

[Michael T.]

Okay, thanks... I was thinking rubbing compound or jewelers rouge... for the very tip maybe some fine emery paper??http://www.n-ssa.org/vbforum/images/smilies/icon_confused.gif

[Hickok]

I just got done casting some Lyman P-H bullets. I smoked my core pin (as well as the mold halves) and the bases came out real nice and smooth. Just a thought!

[norman horne, 12321]

Best thing I've found to smoke (carbon-coat) your mold for good bullet release, is what we in the South call "lidard" (actually lightwood). This is the heavily resinous wood from the pine tree; it lights easily and burns with a thick smoke. It has been used hundreds of years to start fires in stoves, fireplaces, and heaters. Growing up, I was told that it is formed when a pine tree dies or is killed in the spring when the sap is up, as opposed to cold weather, when the sap is down.

[Maillemaker]

We always called that "fatlighter" in scouts.

What I read was that smoking does not aid in bullet release from the mold. In fact the smoke residue is mostly gone within 20 bullets or so.

What the smoke does is act as a thermal transfer barrier between the molten lead and the mold blocks. This allows you to get better bullets quicker when the mold is not yet up to temperature.

If you start with a hot mold I don't think the smoke does much for you.

Steve

[hp gregory]

it would seem that almost every mold wants a little bit differant procedure when it comes to casting a good bullet. canting a mold under a bottom pour sorta copys what you do with a laddle. i think this pushes the air up and out of a mold. i know i have a lot of molds that this works with. some molds have vent lines cut in their face. if these stay open they can help event the air. it seems to me that the hardest bullet to pour correctly is a hollow base minie and these are the only bullets i use a laddle to make. i have found canting the solid base bullet molds is enough to get good bullets when using a bottom pour. the pesky hollow base minies seem to need the laddle. im sorry to say that weighting the bullets is the only true way of knowing if there is a cavity inside the bullet. it takes some time to do even on a digital scale but for those who want the best ammo i find that its worth the time taken to do it.

hp

[Southron Sr.]

I head down to the local hardware store and pick up a spool of 50/50 lead/tin solder wire. (NOT the acid core wire,use the solid core wire) Then I throw some of the solder wire into a pot of molten lead and stir it in.

The tin causes the molten lead to fill out the mould much better and prevents voids in the cast bullets. A little bit of tin in the mixture does not appreciably harden the Minie Balls.

Try it and you will like it as your Minie Balls come out brighter and much better!

[Michael Bodner]

Ask anyone in the casting industry. Voids are a big deal on ANY casting...

[bobanderson]

You guys DO know this thread is 6 years old, right?

When I cast minies, from pure lead btw, I always preheat the base pin with a propane torch. The first bullet is usually a keeper and I never get voids.

My 2 cents worth.

[Maillemaker]

In the past 6 years I finally came to the conclusion that the only way to get reliably weight-consistent hollow-based bullets was to ladle pour them, starting with the mold held horizontal and then moving to vertical as it fills.

I've often thought it would be interesting to make a custom sprue plate that had little "deflectors" on the side of the inlet hole so that with a bottom pour pot you could start the pour nearly horizontal and then move the mold to vertical it fills. As they are, I've tried every kind of trick I could think of with the bottom pour pot and even when you can't see the voids the weight variation leads me to believe they are still there.

It's possible, too, that it's the speed of the incoming melt that matters. I think a ladle-pour fills the mold much faster than the Lee bottom-pour pot.

Steve

[Hal]

I have come to same conclusion, Steve, in regards to ladle pouring beginning from the horizontal. I get much more consistent results that way.

[Southron Sr.]

Like I said in my earlier post, a little bit of TIN mixed in your lead pot will cause the lead to fill out the mould much better and greatly reduce voids in your bullets.

Just something I have learned in a half century of casting bullets.

[tackdriver]

Gonna try this. How much tin is a little bit added to your standard Lee pot?

[Maillemaker]

I tried the bit-o-tin thing. It does make bullets fill out better. But I'm sold on the ladle pour for hollow base bullets. Plus the unknown quantity of tin always makes me nervous.

Steve

[Rick R]

I completely eliminated visible holes by the following:

Ladle pour, an open top old hand forged one that holds enough lead to pour off the dirty stuff and fill the mold with clean lead with enough left in the ladle to keep pouring over the mold during start up for getting up to temperature. I pour fast and at a canted angle leveling off as I stop the pour. I cast very hot, they'll come out a straw to a blue color. I back the heat down to shoot for a straw color and an occasional blue hue.

I use the old Lyman 575602 which is the hardest mold I have ever used regarding the air pockets.

If you have visible holes in one out of ten you likely have holes in the nine "good" ones, just slice them open and weep. I cast thousands (it's been years) with no holes and stopped being all that curious to weigh or dissect. I figure the process is stable, verified by inspecting so I'm good to go. I still qualified my initial statement because it is not an absolute certainty. At least you know the basis for my conclusion.

Rick
1st USSS

[Hal]

What I have seen recommended is 1%-2% tin. It ain't much. It's not enough to harden the lead, just enough to reduce the surface tension a bit for good flow. If you are worried about getting the right amount, don't do it to every pot separately. Do it when you "smelt" down your big ingots and make little ones. You can weight it and put in a measured amount of tin and then ALL your ingots have the same amount of tin with no guessing.

Having said that, I used to add tin to my pot. And still do on occasion, when I'm having fill out problems, but since I switched to the RCBS Hodgdon mould, I find I can ladle pour without the voids I used to get with the Lyman 575213OS I used to use, and no longer find it necessary to add tin in mt minies. I do add it to my carbine bullets when I can't seem to get rid of rounded corners.