Weight Of Lead By Volume

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Dr. Howell: In your reference library do accept any information on the weight of pb by book (grains/cubic inch or ounces/cubic inch existence much preferable to grams /cubic centimeter)? There's a limit to how many conversions I am likely to go right in whatever one day. <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" />
I would like to summate how much weight I could proceeds in a bullet past altering its length a certain amount and ultimately get a mold made to do it.
Many cheers.

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Campfire Oracle

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Pure lead weighs (nominally) 0.4096 pound per cubic inch. That's 0.4096 � 7,000 = two,867.2 grains.

Only your bullets -- cast or jacketed -- aren't all lead, so the workable weight per cubic inch is something less -- and I can't guess how much less. There's an equation for finding the weight of an alloy or heterogeneous bullet relative to the weight of the aforementioned volume of water -- by weighing the bullet suspended (by an substantially weightless thread or wire) in the air, and so in h2o. Some of the ameliorate scales used to have a double claw on the axle and a beaker platform on the base for making these two weight measurements.

Only I oasis't seen that equation in decades, don't remember information technology, and don't know where to find information technology or how to derive it. I'g sure that some of the better educated guys here can supply or derive information technology and will mail service it here. (I hope so -- I've wanted to recover that equation, for lo! these many years!) If I discover it, I'll post it. It may be more undecayed than hardness for comparing cast-bullet alloys for their relative consistency.

"Good plenty" isn't.

E'er have your responsibilities seriously only never yourself.

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Campfire Oracle

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Well, FWIW, I think I've fingered it out. I'll give my reasoning, and somebody tin can check it for united states of america.

Former Archimedes first figured-out that an object in a liquid is buoyed-up, supported, or "lightened" by a force equal to the weight of the liquid that it displaces. A bullet suspended in water, therefore, must weigh its weight in air minus the weight of the water that it displaces. Its relative density -- its weight in air divided by the weight of the water it displaces -- is therefore its weight in air divided by the deviation in its two test weights.

If I'chiliad right, and then the "lost" equation is

10 = a/(a-b)

if
a = weight of the bullet suspended in air
b = weight of the bullet suspended in water
ten = specific gravity

The weight of the bullet per cubic inch, then, is the weight of a cubic inch of water (virtually 0.0361 lb or well-nigh 252 to 253 grains) times the bullet'due south specific gravity equally determined above.

Only at this time of the night, after a day like today, I'm non the first bit certain that I've figgered this right. <img src="/ubbthreads/images/graemlins/dislocated.gif" alt="" />

"Good enough" isn't.

E'er take your responsibilities seriously simply never yourself.

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Dr. Howell:

The weight in grains per cubic inch is close enough for my purposes. If I really desire to fine tune it I'll cast a bullet in pure lead and compare it to the weight of a bullet from my usual bullet metal and come up with a percentage which should also utilise to the volume of the projected increase. For what I accept in mind an increment in volume of.006 cubic inches of volume would add 17.2 grains of weight to the bullet. In practice it would be slightly less than that (unless I apply that actress metal to produce a two-office soft nose bullet).
Thank you for digging that out.

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On rechecking my volume calculations I found I had erred. Weight increase will actually be closer to forty grains which is pregnant (348 Win). Now to play around with some bullets and a file and see how much meplat will actually feed smoothly through my 71. Ultimately hope to lodge some other mold from Mount Molds that will cast at 250 grains or a flake college.

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Campfire Oracle

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You demand AutoCAD.

Several years ago, a bullet company hired me to redesign the classic circular-nose .38 Special bullet and so popular with cowboy shooters, to give information technology a meplat wide enough to span primers (in tubular carbine magazines), withal maintain the original weight. In AutoCAD, I drew the bullet and got its volume. Then I drew it with the meplat and got its smaller book. Finally, I drew it with a wider begetting band just forwards of the crimping groove until I got the volume support to the original volume.

Later the moulds were in production and employ, I asked the manufacturer and was told that indeed the redesigned flat-nose bullets bandage to exactly the same weight as the unaltered original round-nose bullets. Yous'd observe redesigning to an exact lighter weight domestic dog-elementary with AutoCAD. Trouble is, AutoCAD ain't cheap. (Neither was I -- got $600 for that job.)

"Good enough" isn't.

E'er take your responsibilities seriously only never yourself.

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Bivouac Regular

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Dr. Howell,

Some articles simply leave an impression on the states. This was one sticks in my memory.
I believe the article you are thinking of is: "The Lead Content of Cast Bullet Alloys" by Frederick A. Hohorst. This was in Handloader #75, page 24. Information technology was besides reprinted in The Fine art of Bullet Casting (Wolfe - you knew that!) page 94. The last page has the formula, the beginning page the pictures.

I am new to this forum and accept been looking for a discussion of cartridge efficiency. Your formula is a skilful one just has raised a few questions....