Varying weights?..

[willy]

Just finished casting some 58 cal. Lee r.e.a.l. 440 grain bullets.
Used supposed pure lead
got bullets weighing mostly 440 grains give or take .5

But I also got some that weighed less than 435 grains,,
I can understand maybe a hollow in the bullet accounting for a lighter weight,,
But I also got one bullet at 449.3 and another at 450.7 !!!!!
How can I get such a heavy bullet using the same pot of lead?

[fredj338]

If you look close at a bunch cast bullets, you'll see some fill out more than others in the grooves. Voids certainly possible too. Heavier/larger the bullet the greater the variation. casting & mold temp plays into shrinkage. So some bullets cast very hot will shrink a bit more.

[Dusty Bannister]

Perhaps you have been inconsistent in the grip pressure on the handles or the blocks did not mate smoothly. Also you might have bullets at the beginning of the casting session fall outside the normal range due to cooler temp of the mold as you bring it up to temp.

[Hootmix]

Heat, i have 1 set of DC moulds that if i pour the hole closest to the handles first, my weight comes out closer to same weight, first 5-6 go back in pot.

coffee's ready, Hootmix.

[JonB_in_Glencoe]

Mold temperature variation will do that, so can weak hand grip.

[willy]

Thanks for the replies,,So much to learn,,

[Hootmix]

JonB, is correct,, if i start to getting fins "I" stop rest my hand & wrist the brain is holding tight, but not the hand.

coffee's ready, Hootmix.

[Winger Ed.]

Rumor has it that the alloys in the pot can also drift apart/stratify a little bit if you don't stir it frequently.

[megasupermagnum]

Calipers should give you your answer.

[Dusty Bannister]

Rumor has it that the alloys in the pot can also drift apart/stratify a little bit if you don't stir it frequently.

I thought that this "rumor" has been repeatedly debunked.
From the LASC site

[2] It is a common misconception that because they are less dense than lead, antimony and tin may undergo gravity separation from the melt. Nothing could be further from the truth. In the absence of oxygen or oxidizing materials, melted lead alloys will remain stable and mixed virtually forever. And from Lyman, [3]Perhaps the single most significant error in all the bullet casting literature is the misconception that lead-tin-antimony alloy melts gravity segregate.

[charlie b]

Most of yout bullets within 1gn of each other is doing well. There will be some that are light due to voids. Like said above, the really heavy ones are usually due to not having handles together tightly, or the sprue plate gets loose.

[TurnipEaterDown]

I generally have a bit harder time casting w/ pure lead (as would be normal for a muzzle loader) than I do w/ alloys containing tin, antimony and arsenic. This should be a common experience, and is due to metallurgy and casting characteristics.

As most know, Tin helps in mold fill and can be used at small percentage for muzzle loaders, and makes things easier, but not everyone uses tin as an additive for MZL bullets, and that's half the problem casting w/ pure lead.

It must be remembered that most everything is more dense solidified than in liquid form. (Water is the common exception, but we don't shoot ice bullets...)

Part of the problem w/ pure lead vs. lead alloy in casting bullets is this soldification process.
The metallurgy can be reviewed in the Lyman books most easily for many readers here, and the important part is alloys don't demonstrate a simple solidification process whereas a homogeneous material goes straight from liquid to solid, there is a transformation zone for an alloy, rather than a temperature Point. The pure lead pour goes from liquid to solid at One temperature, and will start to solidify at zones where the temperature is cool enough (outer surfaces, basically), leaving the center to solidify last. If the sprue is already solidifed (exposed to atmosphere at the top of the mold, can solidify early) there is no liguid lead to draw from as the core solidifies and shrinks, leaving voids (porosity) to form inside the bullet.
The alloys don't behave that way. They go through a phase change between pure liquid and pure solid, and tend to draw more material off the sprue as full solidifcation occurs inside the mold (bullet). No doubt, a caster can still have an inadequate sprue w/ an alloy, it's just harder to do wrong.

The practical implication of this is easy to see w/ full pots shut off to cool in colder environments -- the pure lead pot will start to solidify at the surface and will often form a divot in the center that has what appears to be cracks or gaps at the center of this divot.
The solidifying lead has pulled material from this center as it contracts while solidifying from the edges in.
The divot with its cracks happens next to the sprue (generally in the base, i.e. we usually use base pour molds) of a bullet too if a person doesn't manage the sprue (thus the pour) adequately.
It is just so much easier to see in something the size of a pot like I use for ladle casting. My pots hold ~ 15-40 lbs, the smallest pure lead, the larger pots hold alloy to keep the % of materials from fluctuating much as material is added when being used (not all WW ingots are really the same).

The sprue can be managed to an extent by what I call 'over pouring': keep adding some material to the sprue as the bullet hardens. This gives the shrinking core something very easy to pull material from and avoids forming that void.

If you have sunken sprues or very little sprue to cut when opening the mold, it would likely benefit your bullet weight consistency to pour more on the mold while the bullet hardens in future casting sessions. This can quickly help deal with those bullets that fall low in the weight distribution.

[JSnover]

I thought that this "rumor" has been repeatedly debunked.
From the LASC site

[2] It is a common misconception that because they are less dense than lead, antimony and tin may undergo gravity separation from the melt. Nothing could be further from the truth. In the absence of oxygen or oxidizing materials, melted lead alloys will remain stable and mixed virtually forever. And from Lyman, [3]Perhaps the single most significant error in all the bullet casting literature is the misconception that lead-tin-antimony alloy melts gravity segregate.

This was recently verified by a CB member.

The OP probably just needs to dial it in a little more with his grip, cadence, temperature... It could even be the pot. Run it near empty and the temperature gets screwey and the pressure/velocity at the spout is reduced; a dribble instead of a stream, so it takes a bit longer to fill the cavity.
With that said, +/- .5 grains on a 440 grain boolit is just a hair under one quarter of 1% That's plenty consistent for most purposes, you pay attention and the skills will sharpen up as you use them.
When I first started, I was getting the same thing (500gr 45-70) and decided it was close enough: time to shoot. Soon enough my weight variation was down to about +/- .2 or .3 grains.

[dverna]

I generally have a bit harder time casting w/ pure lead (as would be normal for a muzzle loader) than I do w/ alloys containing tin, antimony and arsenic. This should be a common experience, and is due to metallurgy and casting characteristics.

As most know, Tin helps in mold fill and can be used at small percentage for muzzle loaders, and makes things easier, but not everyone uses tin as an additive for MZL bullets, and that's half the problem casting w/ pure lead.

It must be remembered that most everything is more dense solidified than in liquid form. (Water is the common exception, but we don't shoot ice bullets...)

Part of the problem w/ pure lead vs. lead alloy in casting bullets is this soldification process.
The metallurgy can be reviewed in the Lyman books most easily for many readers here, and the important part is alloys don't demonstrate a simple solidification process whereas a homogeneous material goes straight from liquid to solid, there is a transformation zone for an alloy, rather than a temperature Point. The pure lead pour goes from liquid to solid at One temperature, and will start to solidify at zones where the temperature is cool enough (outer surfaces, basically), leaving the center to solidify last. If the sprue is already solidifed (exposed to atmosphere at the top of the mold, can solidify early) there is no liguid lead to draw from as the core solidifies and shrinks, leaving voids (porosity) to form inside the bullet.
The alloys don't behave that way. They go through a phase change between pure liquid and pure solid, and tend to draw more material off the sprue as full solidifcation occurs inside the mold (bullet). No doubt, a caster can still have an inadequate sprue w/ an alloy, it's just harder to do wrong.

The practical implication of this is easy to see w/ full pots shut off to cool in colder environments -- the pure lead pot will start to solidify at the surface and will often form a divot in the center that has what appears to be cracks or gaps at the center of this divot.
The solidifying lead has pulled material from this center as it contracts while solidifying from the edges in.
The divot with its cracks happens next to the sprue (generally in the base, i.e. we usually use base pour molds) of a bullet too if a person doesn't manage the sprue (thus the pour) adequately.
It is just so much easier to see in something the size of a pot like I use for ladle casting. My pots hold ~ 15-40 lbs, the smallest pure lead, the larger pots hold alloy to keep the % of materials from fluctuating much as material is added when being used (not all WW ingots are really the same).

The sprue can be managed to an extent by what I call 'over pouring': keep adding some material to the sprue as the bullet hardens. This gives the shrinking core something very easy to pull material from and avoids forming that void.

If you have sunken sprues or very little sprue to cut when opening the mold, it would likely benefit your bullet weight consistency to pour more on the mold while the bullet hardens in future casting sessions. This can quickly help deal with those bullets that fall low in the weight distribution.

Best answer. Some of you who answered must not have realized the OP was casting pure lead.

[megasupermagnum]

I've only casted with the 50 and 54 caliber LEE's, but they drop pretty much what they say in pure lead. If the OP is getting 450 gr bullets, there's really only one thing that can do that. The mold wasn't fully closed.

[TurnipEaterDown]

As one of his observationsThe OP stated: "But I also got some that weighed less than 435 grains,,"
My post was to address that observation.

There is no way (in a practical sense, i.e. as applied to hobby bullet casting) to produce a notable broad range increase in bulk density of a solidified metallic compound that is cast w/o voids. My post responded to voids, and resultant observation of "light" bullets.

Yes, bullets weighed as heavier than intended with intended alloys from a properly cut mold, are often are due to gross error like improper mold closure, and can be diagnosed often w/ gross measurement. This should be observable as well by a exceptionally well defined mold parting line on the as cast bullet, or even a fin. Sometimes this won't be evident on a bullet cast w/ pure lead, as the surface tension of lead is higher than lead-tin, lead-tin-antimony, or lead-tin-antimony-arsenic alloys, and the flow into the mold gap is hampered by this surface tension.

However, comparing the statistical spread in weight of a cast lot of bullets to the advertised mold nominal intended bullet weight is not a very good way of determining if some bullet is cast w/ improperly closed mold blocks.

As alluded to, careful diameter measurements will determine that.
Mold blocks improperly closed do not produce bullets that are just "big" though.
Such an error produces bullets that are too large in one diameter measurement, and usually "OK" in another. Not holding the mold block fully closed will produce an Oval bullet. The mold cavity cutter will still predominantly control the bullet diameter on the dimension taken at the mold parting line. Loose hold, or contamination of mold faces will affect the dimension perpendicular to the mold faces most predominantly.

The OP stated he had two problems, and my post was to address one.

Finally, back to the comparison of measured weight to that stated on the mold:
Don't freak out when casting bullets of alloys if the weight of a bullet doesn't match the mold spec. I have seen this vary an easy 6%.
Those differences are most often traced to alloy constituent percentages, and if the mold maker accounts for gas checks, lube, etc, and if you are weighing bare bullets, finished bullets, etc.
On a mold intended to cast from pure lead (like a LEE REAL), which has no GC, and isn't intended to be lubed until it is pushed in the bore, there can still be notable weight variance between your bullet and the mold spec. It comes to machining tolerance.
Lee makes an acceptable product, and the price point meets a defined market demand.
To expect that they hold tolerances in mold cavity major diameter, circumferential run-out, length, sprue plate flatness and hence gap to mold block face, etc., like one would find in common roller bearing manufacturing (needle or ball), or even automotive manufacturing of something as simple seeming as a differential for a live axle or FWD transmission would be to expect the inconceivable. (No one in the posting stream has stated explicitly that they believe so, the comment is to illustrate a point on expectation, vs. manufacturing reality for defined design criteria.)

LEE makes a usable product: BUT, to measure weights as cast with one of their molds and compare to product label description and utilize as diagnosis is to take an unwarranted leap of faith.
It just "doesn't pay" to produce a product so manufactured, OR, to put another way: If the bullet is Cast Well, i.e. w/o voids or notable band forming issues, then it won't matter two spits if the weight is a few grains off stated. What matters is casting quality and weight consistency.

[Bigslug]

Standardized on locking mold handles pretty early on: https://www.buffaloarms.com/steel-mold-holder-handles-cthandles.html

Adjustable, kind of like vise-grips to lock your blocks together with uniform tension. Saves a lot of grief.

[Wayne Smith]

Lee six cavity mold? Holding the sprue cutter handle will open the mold just a tad, creating larger boolits. Be careful how you squeeze these mold handles.

[willy]

This was recently verified by a CB member.

The OP probably just needs to dial it in a little more with his grip, cadence, temperature... It could even be the pot. Run it near empty and the temperature gets screwey and the pressure/velocity at the spout is reduced; a dribble instead of a stream, so it takes a bit longer to fill the cavity.
With that said, +/- .5 grains on a 440 grain boolit is just a hair under one quarter of 1% That's plenty consistent for most purposes, you pay attention and the skills will sharpen up as you use them.
When I first started, I was getting the same thing (500gr 45-70) and decided it was close enough: time to shoot. Soon enough my weight variation was down to about +/- .2 or .3 grains.

I think you nailed it,,I could definitely see the difference in the stream of lead when the pot got closer to being empty. And I know there was a big time gap a few times while casting which would have let the mold blocks cool,My buyers all look filed out and bright and shinny,,But the scales and the mic showed they were far from perfect,,I willtake you all’s advise and give it another go,,