Making a mold cast small


May 28, 2013, 12:50 AM
Okie, so I have been casting for a couple of years now, but I have not run into this problem with LEE molds. I purchased the .476-400 mold and it casts oversize so that a loaded round does not chamber. LEE is not taking special orders at the moment, and I am can not justify the $50 right now to get Magma to make me a die for my Star sizer.
I hear oversize bullets are a problem with this mold right now. I was wondering if there was an alloy mix or method which might cause the bullets to shrink a bit more coming out of the mold.
Currently I am using straight WW and water-quenching them out of the mold for convienience. My next step is to try casting without quenching, that takes up more space than I have set up currently. The bullets currently drop at .479-.480. I am loading these for a Taurus in 480 Ruger, which seems to have pretty tight chambers.
Thanks for any insight.

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41 Mag
May 28, 2013, 05:04 AM
You can try increasing the heat on your alloy a bit, and casting with a bit hotter mold. You will just have to play with it but it should get you a bit smaller bullet to drop. The hooter your mold is the smaller the bullets will drop. Once they start falling out frosted, give a few pours and then check a few against what you already have.

Also bear in mind that after a week or two they will have grown a bit also. I usually wit around two weeks with similar alloy to size, and that seems to help out greatly in keeping them within the size range I need.

May 28, 2013, 06:59 AM
You can size them down to .476.

What are you sizing and lubing with now?

May 28, 2013, 07:18 AM
Try cutting that wheel weight alloy in half with pure lead. A more pure lead alloy will drop from the mold smaller in diameter.


May 28, 2013, 08:54 AM
Thanks 41, I will try that.

Steve, I am tumble lubing them, but not resizing them. All my other LEE molds work without resizing, but I do have the resizers for them to put on gas checks. No one has the lee sizer in stock or I would have had it 5 months ago. If I owned an RCBS or Lyman sizer, it would be an easy decision.

USSR, I will try that as well. I was wondering if something like that might work. I only have a couple thousandths to go, so maybe I can cut the WW and increasing heat on the mold if necessary.

May 28, 2013, 01:35 PM
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 .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
from 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

May 28, 2013, 02:19 PM
These guys are right on the money of course.
In addition to the comments above, I humbly submit the following links for your perusal: (The main index) (about halfway down this page they specifically discuss the amount of shrinkage one can expect based on different alloy contents) (another compendium of bullet casting/loading knowledge)

tightgroup tiger
May 28, 2013, 04:49 PM
This is a really interesting post, It answered a lot of questions for me as well.

May 28, 2013, 05:19 PM
That information provided above is right on. I've been casting off and on for the last 20 years with RCBS and Lee molds. I've never known that a mold would produce a bullet that didn't need to be sized. There is just too much variation as to how tight the mold is held together, the temperature of the pour, the alloy content as it sits hot in the pot without stirring, and how i am holding my mouth at the time I pour. I've used some molds that were supposedly pretty good that would still produce a bullet not concentric within .0005-.0001. Therefore I always size everything I cast. It makes it easier to change the sizer insert to get that over-sized pistol bullet when desirable without having to get a second mold.

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