Lyman rould ball mold accuracy

[Robin Henderson]

The post on the 58 caliber molds got me to wondering what kind of accuracy others get with their molds...That is, does your .575 marked mold cast a .575 ball? Mine mics .572/.573. I have a .445 Lyman that cast closer to a .440 than .445. and others vary as well. I wonder if it's the lead that I'm using? I have probably a lifetime supply of x-ray room salvage so that's what I'll be using.

[Eric Krewson]

I have a lyman .535 mold that throws a lopsided ball, .535 on one side and .528 on the other side.

I got the mold on a trade and suspect the guy stuck me with a bad mold to get rid of it but can't prove it.

[Maven]

In my experience, bullet molds (moulds) rarely cast to a given dimension, i.e., both diameter and weight for several reasons.  To wit, the alloy you and I use may not be what the manufacturer used to "spec' his molds; because manufacturing tolerances vary a tad; and because our casting techniques vary (temperature of melt; bottom pour v. ladle pour; cadence of casting; etc.).  That being said, you make up the difference between as cast and specified diameter by sizing the bullet to suit for cartridge guns or by varying the thickness of the patches you use for ML'ers.  E.g., I have a Lyman mold which is marked .490", but the pure lead "as cast" diameter is .487" - .488".  That RB does best with a .021" cotton duck patch rather than the .018" pillow ticking patch I had always used.  Moreover, I've recently found that the same gun is even more accurate when I use a .492" (as cast) RB cast from a RCBS mold with the cotton duck patches mentioned in the previous sentence. In short, unless the mold is grossly over- or undersized, it isn't the main source of inaccuracy. 

Here's a link to some targets I shot recently to illustrate the above,  Posts #1 and especially #2 are the ones you want: http://tradmla.org/tmaf/index.php?topic=22347.msg209723#new

[okieboy]

 Is it possible to cast balls from a mold, and then use them as laps to improve the roundness of a mold?

[Bob Roller]

The post on the 58 caliber molds got me to wondering what kind of accuracy others get with their molds...That is, does your .575 marked mold cast a .575 ball? Mine mics .572/.573. I have a .445 Lyman that cast closer to a .440 than .445. and others vary as well. I wonder if it's the lead that I'm using? I have probably a lifetime supply of x-ray room salvage so that's what I'll be using.

Those moulds may have been cut with worn tooling. I have a .58 round ball mould that I bought from
E.M.Farris in 1953 and it is still good and I can't begin to estimate the number of balls that have dropped
from it.In 1953 those blocks cost the sum of $3.50 new in honest currency.Make a heavy sprue cutter/plate
for these moulds and then get them really hot and see if there is any improvement in weights and dimensions.
Been there and done that,it helps.

Bob Roller

[P.W.Berkuta]

In my opinion molds that are made by reputable companies are made and inspected to a high standard. That being said there are times that quality control is not at the same standard all the time. This may lead to some out of tolerance molds leaving the factory. That is why they have a customer service department. All that said you just might look at the tool you are measuring with. They have a tolerance rating on them also so you might be getting a false measurement - a few thousands here and there do add up. In the end I would not sweat the small stuff .

[hanshi]

Molds from Lyman, Saeco, Lee, RCBS, T/C and others make up my stash for casting.  My Lyman .445" mold drops ball that varies a .001" to .002" depending on the way I rotate the ball while measuring.  I would call it a average of about .443" (+ or -).  The ball shoots well enough to alternate with ball cast with my Lee .440" mold.  In round ball form, the Lee molds cast the most dia. accurate ball in all calibers and the most uniformly round ones. 

[D. Taylor Sapergia]

Some of my iron molds cast balls as advertised.  But some do not.  Most noteworthy is my .610 Lyman blocks...they cast .613" balls, but they are round.  My Lyman .595" mold casts balls with a bit of a peak at the sprue, kind of like a football in that area, but they shoot into one hole so who cases.

[T*O*F]

If you want your balls to be mold size, and they aren't, cast them hotter.  Both lead and mold.

[Daryl]

I use nothing but the purest lead I can find.  X-ray room wall sheeting.

I have a DC  Lyman mould to give away to a good home - a DC mould I bought from someone on this site. It casts a .400" X .400" ball in one cavity and a .400" X .394" in the other one. I will mail it, you pay the shipping.

I have a .570"(marked) Lyman mould that casts .573" X .574"- close enough to perfect for a .58 rifle.  .575" X .575" would have been better, but not from a .570" mould.

My .395" Lyman single cavity blocks cast a .378" X .378" ball - beautiful in a .40 Goodoien bl. with nice thick patch.