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Test the assertion:

Smoking the Mold is Necessary for Lee Molds to Cast Good Bullets.



 

Experiment 110824-A

Setup:

Start with a new Lee mold. 358-158 SWC (TL)

Cast bullets with known good alloy.

Alloy:

Reclaimed bullet cores   97.5%
Tin                                2.5%

This alloy is known to cast good bullets with iron molds and with other Lee molds.

Start casting as fast as possible to heat up the mold. In the beginning I get the normal cold mold bullets. After the mold is hot enough to producing significant frosting, the bullets still refuse to fill out properly. The flaw is similar to wrinkled but I call it "splashing". It looks like a splash of lead cooled on the side of the mold and the remainder of the bullet poured behind ( Inside the cavity from ) it.

Bullet weights before smoking average   161.24

Bullet weights after smoking average      161.86

Both averages were the average of 25 bullets selected pseudo randomly. ( Reached into the box and pulled out a handful then counted out 25 and threw the remainders back into the box. )

It is interesting that the smoke coating bullets are heavier than the non-smoked wrinkled bullets. This is a good measure of the weight of the voids caused by the wrinkles.

Bullet Diameter Before and After Smoking

Diameter Pre Diameter Post
3603 3622
3597 3602
3606 3635
3601 3608
3603 3623
3627 3641
3619 3620
3616 3627
3627 3620
3613 3613
   
   
   
Diameter Pre Diameter Post
3603 3622
3597 3602
3606 3635
3601 3608
3603 3623
3627 3641
3619 3620
3616 3627
3627 3620
3613 3613
Total 3611.2 3621.1
Avg 361.12 362.11
SD .707 .631

 

These measure the diameters of 10 bullets selected at random. This is not a good method. Next time, I will use only bullets from the same cavity.


   
Representative of first bullets cast from a new, untreated  cold, room temperature Lee mold.  It has all the deficiencies normally associated with cold mold. In this case the metal was not cold, it was 750 degrees.

Click on the image to expand it and notice the following.

Huge wrinkle running the entire length of the bullet.
Smaller wrinkles around the nose of the bullet.
There are eight driving bands and every one of them is rounded. Rounded means they are not fully formed. They should be flat on top with only slightly radiused corners.

And. You are correct. It is not the same bullet. I included it here because it is the best photo I have of rounded driving bands.
Bullet Flaw
After the mold is well heated, this is the best we can do.  Note that the most bands are mostly flat on top with slightly radiused edges and the lube grooves are flat on the bottom.  The front driving band is still rounded right at the top center of the image. The same band is well formed on both the left and right edges of the image.

It still has the severe wrinkle running lengthwise.
Bullet Flaws 
Continuing to cast, the mold becomes hotter and the bullets begin to frost. By 'frost' I mean the  appearance of a crystallized surface at the edges of the driving bands. It looks like the corners of the driving bands  froze and chipped off. As the mold temperature continues to rise, the frosting will cover more and more of the bullets surface. Frosting is always caused by the mold being too hot.

Bullet Flaws 
For the experts: 

Before you say that every flaw listed above could be caused by contaminated metal or metal with too little tin content, let me say "You are correct".

But in this case they were not.  The bullet in this image was cast from the exact same opt of metal immediately before starting the experiment to "prove up" the alloy.

This is a representative sample of about 60 bullets cast in a Ballisticast mold. I threw away the first five fillings and then saved the next 15.

Please expand the image and not the perfection of the bands and also not the tooling marks on the walls of the cavity.

Hensley & Gibbs #51  
I next smoked the mold cavities with a butane fire lighter. About two bucks at Wallmart.

I got at least five times as much smoke on the face of the mold as in the cavities.  For some reason I don't understand, that really does not like to get into those cavities.
Lee Mold 
After smoking, I wiped away as much of the soot as possible from the face of the mold blocks with a dry paper towel.  Taking care at the time to not remove any of the coating from the walls of the cavities.  Lee Mold Smoking 
I threw away two fillings of the six cavity mold to give it time to re-heat and this is the very first bullet to drop from the third filling.

I then cast approximately 250 more and rejected less than a dozen.
Lee Bullet 
   
   
 

 
 

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