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Do you have to size all bullets after casting what are molds or alloys you dont have size i know about the lee tumble lube moulds so other ideas please.
 

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Piney Woods Moderator
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The need to size a cast bullet depends on how big it is when it drops from the mold. I have several molds that drop a bullet .002 over the bore size which is just right. I just tumble lube these and shoot them. Several of my molds drop bullets much to large to shoot so I have to size them within .002 of the bore. I tumble lube these first then run them through the sizing die and tumble lube again. I use several of the Lee Tumble lube molds with excellent success.
 

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The alloy used will determin the diameter from the mould.
Bullet 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 .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 Cast Bullets
 

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You need to remember there is not an easy answer to your question.
Barrel dimensions differ between manufacturers and cartridges.
Older rifles often have a different throat than new manufactured firearms, even when they are chambered for the same cartridge.
Lyman has a new edition of their Cast Bullet Handbook ready for release. If you get a copy of this book you will see a chart with bullets cast from the same mold using different alloys and their respective diameters. The chart is quite helpful in estimating as cast diameters of bullets.
You also need to be aware the various mold manufacturers traditionally use different bullet diameters for bullets intended for use in the same cartridges.
Ideal and then Lyman traditionally used oversize bullet diameters, until recently when Lyman reduced some of the bullet diameters. Ideal and Lyman both made molds marked with a “U” which were undersize. The “U” number molds were available on special order.
In general terms the fit of the bullet in the throat of your rifle or handgun is far more important to accuracy the bullet diameter Vs bore or groove diameter. I typically shoot all of my cast bullets “as cast” and lube by hand or tumble lube the bullets. You will be well served by studying a copy of the Lyman Cast Bullet Handbook and as the latest edition is now “overdue” at the vendors it will certainly be available shortly.
 

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As a collector and caster I have many molds: Ideal, Lyman, H&G, B&M, LBT, Lee, NEI and several other lesser known brands.
I have rifles from across a broad time line.
You have not mentioned what rifle and cartridge you are loading for. In general terms you will find the current Lee molds casting bullets at or very close to their specified diameter.
Some other brands of molds are also very close. If you ask Veral Smith at LBT for a mold which casts .401” diameter using a 1 – 10 mix, your bullets will be exactly that.

Cast bullet fit and lubricants are not difficult to understand once you have the books for study. In the book section there is a link to Phil Sharps Complete Guide to Handloading on a PDF file. Sharpe’s book will give you a great deal of basic information on bullet fit and lubrication.
 

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You should always size a cast bullet IMO. There are standard diameters for a caliber. 38/357-.358" 44mag-.430" 45acp -.452" Sizing to these diameters will serve you well for 99% of firearms. Rifles tend to run larger 30-30 30-06 308 - .309" to as large as .311"
 

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Piney Woods Moderator
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I use mostly Lee aluminum block molds. For general all around shooting the Lee tumble lube bullets are hard to beat. Mold, tumble lube and shoot.
 

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The tumble lube bullets are specifically designed to need no sizing. Many have observed before that shooting bullets as-cast, rather than sized, improved accuracy and decreased leading. This seems to be due to two things:

One is simply that many people cast bullets too hard and size them too small for the powder charge they are using. At the standard 0.001" oversize diameter, a hard bullet can fail to enter the bore straight enough for a completely satisfactory seal. A bullet that diameter needs to be soft enough for the propellant pressure to upset it to fill the bore well. An alternative is to use hard alloy, but also make the bullets slightly larger. 0.002" over groove diameter has often been found to be more satisfactory for harder bullets, as the extra diameter does a more certain job of achieving the bore seal.

A second reason has to do with lead alloy metallurgy. When the bullet is sized the the surface grain structure is disturbed. Lead alloys are funny things, often taking a couple weeks to fully harden after water quenching, and having antimony migrate slowly through them, and so on. Apparently the surface disturbance effect doesn't stop at the moment of sizing, but causes an effect that spreads into the surface, leaving the bullet alloy easier to smear and therefore leave more leading behind. Bullets sized by being shot down a bore don't have time for that surface effect to spread before the bullet is out. So they often lead less.

If you go to an extremely hard alloy, you can avoid that second problem being significant. This is the strategy Beartooth Bullets uses, being about BHN 21. But Marshall's technical manual does show accuracy improvement in revolvers using them 0.002" over groove diameter, which is consistent with the first issue.

If you are just starting out, buy the Lee one and two cavity molds by all means. Do your experimenting and make your mistakes on something inexpensive. When you get the hang of casting, then worry about pricier molds that are more durable and have more cavities for improving your production rate.
 

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I stick with 20:1 alloy and BP and .002 over groove dimension.....................an old formula tried and true. No gas checks are required and hardness is fine for the velocities involved (<1400 fps). The alloy fills the molds great with nice sharp corners/edges. If you are going to push the velocities up this will not work well.

Mc
 
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