What's going on with my bullet diameter?

[KirkD]

Yesterday, I had my very first casting sessions, using my spanking new .460" 500 Grn. RN Saeco 2-Cav. Gov't Bullet Mould. I was told by various people that this mould drops them at around .460 or .461. Today, I got the electronic calipers out to see what the bullet diameter was, as I was making a cookie cutter to do some pan lubing. My largest .45-70 sizing die is only .459. Well, to my shock, the diameters of my bullets that I cast yesterday were only .457-.458! I've heard that bullets shrink after you cast them. I've no idea what alloy I used yesterday .... I melted down some soft cast 35-55 bullets that were so badly cast by someone else that I couldn't use them. Do you think I got a bad mould, or did my bullets shrink that much. How can I get more diameter and less shrinkage?

[Blammer]

check you're .460 dia bullets and see if they are round or a bit "oval"

you may have been 'beagling' them and didn't know it.

[montana_charlie]

1.) I was told by various people that this mould drops them at around .460 or .461.
2.) Today, I got the electronic calipers out to see what the bullet diameter was,
3.) My largest .45-70 sizing die is only .459.
4.) the diameters of my bullets that I cast yesterday were only .457-.458!
5.) I've heard that bullets shrink after you cast them.
You supplied five things for us to think about while trying to come up with an answer for you, and Item 3 has me confused.

Did you mention the diameter of your largest sizing die just because that information fell out of your brain and into your typing fingers...or are you measuring bullets that have been run through that die?

If 'soft' bullets come out at .458" (or less) after going through a standard .459" die, that is not at all surprising.
CM

[44man]

I don't think he sized them. I think he is saying his boolits came out a lot smaller then he expected, too small for his sizer.
If the lead is soft with only a little tin, they won't get larger but if they have antimony in them they will expand in time.
Try casting hotter to expand the mold more.
If all you cast is .457 to .458, you are stuck with an undersize mold. Call Saeco if you need larger.
You can beagle the mold but the boolits won't be round.

[KirkD]

To clarify things, I mentioned that my largest sizing die was .459 to explain why I was pan-lubing (i.e., I didn't want to lube my bullets by putting them through a .459 die). However, with the undersize bullets, I am now lubing them by putting them through the .459 die. Only lube is added; the bullets are too small to loose any diameter in these larger dies. The diameter of the bullets was taken before putting them through the die. So the bottom line is that my bullets, out of the mould and without any sizing, are quite a bit smaller than .460.

The next time I cast, if I start with wheelweights, what should I add to the mix to reduce shrinkage, assuming it is shrinkage and not an undersize die?

[454PB]

Add antimony to increase diameter. However, don't expect anything dramatic. I've found that a mould that casts .452" in WW alloy will only throw a .453" to .454" boolit in linotype. So....you can gain diameter at the expense of producing a harder and lighter boolit, and from a more expensive alloy.

[w30wcf]

KirkD,

Molds from mold makers that use "cherries" to cut the cavities can vary a bit in dimension depending on how many times the "cherry" was sharpened. When it gets down to a certain diameter, a new "cherry" or "cherries" are made. I don't know what the tolerance is that Saeco specs their molds to and in what alloy.

If you made your bullets from a lead/tin mix, you would probably gain around .001" in w.w.

Good luck,
w30wcf

[Bass Ackward]

1. Mics are the best way to measure the true diameter of bullets.

2. Check your bullets for roundness. Or I should say out of roundness. This can give you a clue to what is happening. I assume that this is a new mold.

How a metal expands when heat is applied will vary based upon the stress in it do to the machining of the block and then again for the cavities. To a degree, the stresses will come out of it. During this process, some mold cavities open up. Some blocks elongate the cavity. But some close in too, if this is the path of least resistance. This is some of what gives each mold a .... personality.

Three heating and cooling cycles will tell the tail as the mold breaks in, then what you have and what it does will be what you get. You may want to try casting a little cooler next time too. See if this makes a difference. I would refrain from using any damp rags or such to cool the mold to prevent warpage. Until it settles in anyway. Just mold a little slower. See how it wants to be run and if this helps.

[KirkD]

This is a new mould. I just measured several bullets, taking two measurements per bullet. The first one across the very faint lines left by the mating surfaces of the mould, and the other measurement rotated 90 degrees from the first. They are pretty much round, but the very faint hairline raised ridge from the two mating surfaces can give me an extra half thou sometimes. My measurements are telling me that the bullets are about .457" in diameter. Just to compare my electronic calipers with w30wcf's, I've measured some of your bullet diameters, John, just to see what I got. My calipers give the same reading within a half thou, so I don't think my calipers are off. I zero them every time I use them. For my next casting session, I will use wheelweights and tin to see what I get. This time I melted down some soft cast bullets that were of no use to me, so I don't know the alloy.