Weight Variations from Lee 6 cavity mold

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  • Last Post 06 May 2012
IMR380 posted this 20 April 2012

I am casting some bullets for a 9mm with a new Lee 6 cavity mold. I have a thermometer and keep the alloy at about 700 degrees. Alloy is 92% lead , 5% antimony, and 2.90% tin. (14 BHN) This is a tumble lube, 124 grain bullet. My bullets are varying in weight from 120 to 125 grains. This seems like way too much variation. I am casting with a ladle, not a bottom pour. I don't know if this is normal for a 6 cavity mold or not. Might be me and not the mold. Any suggestions would be appreciated. Thanks

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pat i. posted this 20 April 2012

My suggestion would be to shoot the things and not worry about the weight difference. If that's not the answer you're looking for try shooting the bullets segregated by weight compared to a random sampling. Let me know if there's a difference on the target.

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[email protected] posted this 20 April 2012

I have 2 6 cavity Lee's a 125gr. .358 and a 158gr. 358. Niether of the sprue plates are flat, resulting in some of the bullets being slightly longer and heavier than others. They shoot just fine, shooting as good as any comercial bullet I've tried. The Lee 6 cavity produces lots of bullets so you can shoot a lot. ENJOY

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onondaga posted this 20 April 2012

IMR380:

You can check the sprue plate for flatness by shining a light through from the edge and seeing if any light is getting through. Sometimes a pivot screw tension adjustment or an adjustment of the other top screw that guides the plate closed may help. That guiding screw or the guide slot on the sprue plate can also be poorly finished and cause a problem too. I have had to slightly bevel those slot tops to get smooth closing.

If the top plate is warped , that may not show up on a cold mold and only be detectable on a hot mold.  A pouring technique error with ladle or bottom pour can also cause the heat warping detectable only when the mold is hot.. Massive over-pour can overheat the sprue plate middle and warp it.

Casting cadence and pour sequence can also over cool the sprues and hard sprues will leave nubs on the bases of the coolest bullets. Fill the mold beginning at the cavity closest to the hinge and overlap pour from cavity to cavity leaving one continuous but not broad blob of over-pour on the sprue plate.   If your ladle is not big enough to pour all six cavities like that, you have a ladle that is too small and that has caused a problem also. The ladle should be at least large enough to carry twice the amount of metal needed for one fill cycle of all six cavities. That is not a small ladle but works best with  six cavity mold pouring and keeps metal temperature closer to equal for all six cavities.

If you use a small ladle, or you even need to use  two fills of a ladle to fill your mold, That is the problem. Your bullet weight will run all over the place with a small ladle pouring to a six cavity mold.

Gary

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giorgio de galleani posted this 20 April 2012

I too have such Lee mold.

I use a bottom pour Rcbs furnace,not the ladle.I find it easier to fill well all the cavities using the bottom pour spout.

Use the Xlox lube,cheaper than Lees alox.

Used to shoot the things unsized but now I am sizing them to .3575 in a Lee die marked .358.

They seem to feed and cycle more smoothly when they are sized.

Actually even their as cast diameters are not constant.

I hit all the plates in a steel challenge match with a Browning HP with european chamber and rifling.

My new STI Spartan has a US chamber and rifling and shoots 20% smaller groops.

The accuracy of mi bullets is not  worse than the hard alloy  Italiancommecial cast bullets.

And I am not going to contaminate my barrels  with horrible jacket metal.

In the 9x21 ,the caliber allowed by our most intelligent gun control laws,I use old hard wheel weights.Air cooled.

I would leave your weighing and measuring   and segregating of bullets to iron custom  rifle moulds and bench rest  shooting at very long range.

Enjoy your bullets as they come from the mold ,the 9x19 pistols are not extremely accurate,their mission is being reliable, and making short range hits.

At least that is my opinion,everybody is allowed to disagree.

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Ed Harris posted this 21 April 2012

I agree with Giorgio. I believe that with the dipper you are not adequuately overflowing the mold to keep the sprue liquid as long as possible, to compensate for solidification shrinkage. If you weigh your dipper poured bullets vs. bottom pour, generously overflowing the mold and making a large sprue, you will probably find the bottom pour more uniform in multi-cavity molds. Dippers work best for single and double cavity blocks.

While you could weigh and sort bullets, it is easy to become distracted when measuring with micrometers while cutting with axes.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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[email protected] posted this 21 April 2012

I just got done wieghing some of my 158's they range from 160gr to 161.5.Thats pretty good consistency. I use a bottom pour melter.

I also agree with ED Harris's statment said in a different way: Don't worry about the mule going blind just load the wagon.

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Johnny Breedlove posted this 21 April 2012

I go with the rest of the group castem loadem shootem. I only weigh a few to make sure they are close to what the mold is supposed to through.

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IMR380 posted this 25 April 2012

Thank you all for the good advice in your replies and pm's. I will do some work on my technique. This 6 cavity aluminum mold is a different critter than the single cavity steel rifle molds that I have used in the past. Thanks again.

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giorgio de galleani posted this 25 April 2012

As you get accustomed to the use you will find that the Lee 6 cavity are a joy to use ,and you make buckets of good bullets in a short time.

I cast hot and open the sprue cutter as soon as possible.

And have modified the Lee sprue cutting compound as explained by Mustafa Curtess in The FS #185  Jan 2007.Simple ,clever and efficient modification. 

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LWesthoff posted this 25 April 2012

I shot Bullseye Pistol competition for many years, and my favorite (go to) bullet for the .45 came out of a 4 cavity Hensley and Gibbs mold. I used everything from wheelweights to lino and various proportions of mixes of the two. I never weighed bullets - just made a visual check. If they had no visible flaws, I shot 'em. Best I ever did was 1st Civilian Expert, .45 Aggregate, at the National Championships at Perry in 1982.

I don't know what discipline you're shooting with that 9 mm, but my suggestion would be to shoot some of those bullets at the longest range you'll be competing, and see if there's a discernable difference in point of impact between highest and lowest weights. My guess is you'll find that weight spread is nothing to worry about.

Let us know what you learn.

Wes

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Wayne S posted this 25 April 2012

 I think your alloy is to “rich"  for a 9 mm shooting, add some lead and try for about a BHN of 10.  You didn't say if this mold was a TL or conventional design. Bullet to throat fit is more critical than a little weight variance, and the distance's normally shot with auto loaders  the “ME” part of Maximum Effective is the much more  important that a little wt. spread.

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sharps4590 posted this 06 May 2012

I'm going to agree with the others. At short handgun ranges your difference in bullet weight won't make enough difference to notice. When I was shooting heavy, open sighted revolvers out to 500 yards I weighed my bullets but with open sights even that probably wasn't necessary. Other than that they never saw a scale.

I believe, at least for me, that the most accurate casting is done with a dipper such as Lyman or RCBS offer. Once melt, mold and dipper are up to temp you should be able to cast within a grain or two even on very heavy, 400+ grain. bullets.

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