Preventing voids in bullets, an experiment.

[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.