Boolit Size

[Bzcraig]

I think I remember reading about this but can't find it. Here are my questions:
1) Will adding lead to WW change boolit diameter? If so, how?
2) Does a hot mold increase or decrease boolit size?

I'm adding this hoping to avoid potential argument. The reason for the questions are I have a NOE 358135 that drops boolits cast of 50/50 (WW/lead) at 360. I size (Lee push through) these down to.357 for my 9's and sizing .003, though not difficult, is a pita because I then need to trim the lead that is deposited below the base of the Boolit. I have to run my melt at nearly 700* (by thermometer) to get wrinkle free boolits. So is there a way to get my boolits to drop at 358?

[Echo]

I believe softer alloy will shrink more, so you might be casting boolits that mike a few tenths smaller...
And I may be wrong, but it seems that I read somewhere that casting hotter makes the boolits shrink more, too - but I may have it reversed...

[TomAM]

Tin content has a big effect on shrinkage, but little effect on hardness.
Antimony content has very little effect on shrinkage, but much on hardness.
COWW alloy is only about .5% tin, and so casts at virtually the same size as pure lead. Adding lead to COWW won't make a significant change in resultant diameter.

BHN is not a reliable way to predict shrinkage.

Mold block metal expands with heat, so hotter molds make larger boolits.

[Dusty Bannister]

Quote

Tin content has a big effect on shrinkage, but little effect on hardness.
Antimony content has very little effect on shrinkage, but much on hardness.
COWW alloy is only about .5% tin, and so casts at virtually the same size as pure lead. Adding lead to COWW won't make a significant change in resultant diameter.


You might want to compare this with the chart in the Lyman Cast Bullet Handbook, 3rd edition, page 58.
Pure lead 45 cal bullets cast at .4515 and WW cast at .4523 and while WW have so little tin and only about 2.5% antimony, it appears that the antimony is what results in the larger casting. The tin improves the flow of the lead.

For your statement that tin has a big affect on shrinkage the same chart would have to show that Lyman #2 casts larger than linotype. It does not show this, instead it shows that the antimony content of lino results in a larger casting.

[cbrick]

Tin content has a big effect on shrinkage, but little effect on hardness.
Antimony content has very little effect on shrinkage, but much on hardness.
COWW alloy is only about .5% tin, and so casts at virtually the same size as pure lead. Adding lead to COWW won't make a significant change in resultant diameter.

No, that is incorrect. It IS the antimony (Sb) that effects shrinkage. The higher the Sb the less shrinkage there will be. A lino bullet will cast larger than a WW bullet because of the higher Sb. Tin (Sn) will have minimal effect on shrinkage unless your using a high percentage. Here's an example of shrinkage:

Shrinkage - Bullet Diameter, Inches

Alloy .308 .357 .452 Linotype .002 .0025 .003 Lyman # 2 .0025 .0025 .0035 Soft Lead .0035 .004 .005

[TomAM]

Antimony does indeed effect shrinkage. Just not nearly as much as tin.
Linotype casts slightly larger than #2, but has 230% as much atimony.
Linotype has almost 3 times the antimony of WW, but 7 times the tin.

[cbrick]

You'll get very similar results with CWW and pure lead. CWW by tested results have 2% Sb and 0.5% Sn (average) and of course the pure PB has neither. You'll get less shrinkage with the CWW because of the Sb even with the very low Sn percentage.

But regardless, for most casters the difference were talking about is measured in tenths and tenths in reality are kinda insignificant. As the chart I posted shows, the larger the bullet diameter the larger the difference between higher Sb alloys and lower Sb alloys or pure lead regarding shrinkage.

Rick

[Dusty Bannister]

And then there is that old lyman #2. Always something to screw up the theory.

[44man]

Not sure about a 50-50 alloy, not much antimony so the boolits might be as small as they will get or within .0005". More antimony makes boolits larger and will expand more after cool and aged a few days. Tin is what blends the antimony and lead into an alloy on the molecular scale. It has little affect on shrinkage or hardness but does make lead "wetter" to flow and cast better.
Rick has a good chart but that might be just cooling in the mold, might gain back some of that shrinkage with aging. Less with small boolits, more with large, my .476" boolits will gain back .002".
Very hot molds make smaller boolits.
I have a 30-30 boolit that casts .311" and I size .311". I wanted a harder boolit for target so I used 16# of WW's and 3# of stereo lead, very rich in antimony and tin. I water drop.
I just measured both and both are .312" so I gained .001" with age with both alloys.
However the more pure lead the less expansion and boolits cast of pure will be the smallest but to try and shoot that soft from a nine will make you change and I think 50-50 is way too soft as it is.
I would bite the "boolit" so to say and water drop WW metal or even use harder for a nine. Might be one of the hardest calibers to get right.
I don't think you will ever get smaller then you have without a new mold.

[cbrick]

Mold block metal expands with heat, so hotter molds make larger boolits.

Very hot molds make smaller boolits.

This is one of those subjects that can make a guy go cross eyed. I tend to agree with 44man on this one though I've never tried to test it.

Here's why I agree with Jim: Very true that metal expands with heat but (there's always a "but" isn't there?) If you measure the outside of the mold when cold & then heat it up it will measure larger, here's the but, the metal expands in all directions and not just to the outside of he mold. Inside the mold the metal is expanding and thus making the cavities "smaller".

Is that true? Hard science? I dunno, I just now tried again to visualize the concept and am now officially cross eyed but I "think" that's how it works.

Rick

[TomAM]

Have you ever measured a mold's cavity at room temperature, and then at 400 degrees? I have.

Have you measured the relative shrinkage of dozens of alloys in hundreds of molds from 30 cal to 12 gauge? I have.

[cbrick]

Have it your way.

[MT Chambers]

Get ahold of Lyman's cast bullet handbook, it spells it out with all the alloys that are out there.

[M-Tecs]

Very true that metal expands with heat but (there's always a "but" isn't there?) If you measure the outside of the mold when cold & then heat it up it will measure larger,
Rick

True

the metal expands in all directions and not just to the outside of the mold.

True but this is were the crossed eyed part comes into play. Every molecule gets more excited as the tempatures goes up so holes alls get larger. Pick any point on the metal and all atoms are moving away from that point as it get hotter.

Inside the mold the metal is expanding and thus making the cavities "smaller".

Not true

Hard science?

Very much so. 100% psychics and 100% predictable.

It works the same a photocopying something in an enlargement setting. The easiest way to visualize it is for take ten dimes and place them in a circle with the edges touching. Now replace the dimes with quarters. The molecules don't actually get larger but they do move away from each other the same as the dimes and quarters

More detail here http://castboolits.gunloads.com/show...erstand!/page3

[cbrick]

Ok, if that's the science of it. I seem to remember being very clear that I didn't know and it was a confusing issue. For that I got 2 snotty reply's from the same poster on 2 subjests but that's ok, speaks volumes and turns out to be his loss not mine.

Rick

[243winxb]

http://www.redding-reloading.com/onl...-moulds-chartsBullet Sizes & Weights – How to Vary Them
The bullet diameters and weights presented in this list are based on the use of Taracorp’s Lawrence Magnum bullet alloy (2% tin, 6% antimony, 1/4% arsenic, 91.75% lead).

Bullet diameters and weights will vary considerably depending on the lead casting alloy used. This variation can be as much as 1/2% on the diameter, and 8% on the weight among the most commonly used casting alloys. For example, a .358-158 grain bullet might show a diameter variation of .002", and a 13 grain difference in weight.

Of the most commonly used alloys, wheel weights (.5% tin, 4% antimony, 95% lead) will produce bullets having the smallest diameter and heaviest weight, with such bullets running approximately 1/3% smaller in diameter and 3% heavier than bullets cast with Taracorp's metal. Linotype will produce bullets with the largest diameter and lightest weights. This alloy will produce bullets approximately 1/10% larger and 3% lighter than Taracorp. Other alloys of tin and antimony, with antimony content above 5%, will produce bullets with diameters and weights falling between those cast f rom wheel weights and linotype.

Alloys containing little or no antimony will cast considerably smaller than wheel weights and in some cases will produce bullets too small for adequate sizing.

Within the limitations given above, the weight and diameter of a cast bullet can be adjusted by varying the
alloy’s antimony content.

The size and weight of bullets of a given alloy will also vary according to casting temperature. Higher temperatures will result in greater shrinkage as the bullet cools, thereby producing a slightly smaller and lighter bullet than one cast of the same alloy at a lower temperature.

[TomAM]

Ok, if that's the science of it. I seem to remember being very clear that I didn't know and it was a confusing issue. For that I got 2 snotty reply's from the same poster on 2 subjests but that's ok, speaks volumes and turns out to be his loss not mine.
Rick

You state flat out, twice, that I am wrong, and state that you are guessing.
I state that I am not guessing, and share well researched information that the OP requested.
How would you have me respond?

[cbrick]

You state flat out, twice, that I am wrong, and state that you are guessing.
I state that I am not guessing, and share well researched information that the OP requested.
How would you have me respond?

No, I said in one post on one subject that I had no evidence and wasn't sure and I made that perfectly clear. On the alloy you are wrong unless you raise the Sn far above what most use, antimony is the reason for shrinkage or lack thereof.

As for how I would have you respond you've already proven that. Business must be good.

Rick

[243winxb]

[QUOTE] hoping to avoid potential argument. [/QUOTE

[TomAM]

I have no intention of arguing, and yes business is very good.