Does you round ball mold ball very by maker?

[recurve]

I have always used the round balls I bought from Dixons(creek something) marked .490.
This spring  I got a round ball mold  marked .490 green mountain (non magnetic )
It got me wondering if the ball size verys by the manifacture of molds? 
If they say.490 what is the true size (and does it matter) ?
If possable please list you mold maker mic your "cast" balls and list
( I know there are different sizes  used but I'm trying to compare apples to apples for the .50)

And yes I expect other jokes on ball sizes (and does in matter )

[Maven]

recurve, I have RB moulds from various manufacturers and in different major diameters, e.g., .490", .457", etc.  For example, my Lyman and RCBS moulds, marked .490", do not cast exactly .490" using the same alloy and casting technique (ladle, always).  You can test them for accuracy with everything constant except RB mould maker/diameter.  You can also compensate for slight differences in diameter by changing the thickness of your patches.  Btw, the Green Mountain mould is made of anodized aluminum and is of excellent quality.  I also think they made RB moulds for Thompson/Center at one time.  In short, moulds made by different manufacturers, but the same nominal diameter, e.g., .490", do indeed vary slightly in "as cast" diameter.

[recurve]

[WadePatton]

Exact diameter is controlled by the cavity and the alloy. If I recall correctly nearly pure lead shrinks the most and alloyed it will shrink less, giving you balls of differing diameters from the same cavity.

You cannot know exactly what size a mould will throw until you've checked it. The most important thing is concentricity, then you can adjust for the size with patching.  A small amount of "out of round" isn't a big deal, but I have a box of purchased round balls that or OBLONG--badly.  I just thought they were too big for my bore as I had beaten one into the breach and then switched to a .005" smaller ball (which happened to be round).  It was only later that I discovered I'd bought leaden eggs rather than round balls.  The company has changed hands and I told the new guy about it.  He seemed interested, but I never heard back from him again.  I'm just going to document them and recast 'em. Note I bought two boxes from the company and the 530's were fine, it was the 535's that were badly out of round.  I learned my lesson for sure.

My point there is that buying cast balls never guarantees trueness, you have to check.  Just like you have to check your moulds when you get them. Tools dull and cut differently throughout their working lifespan. QC is supposed to keep it "within specs" and usually does.

Contact the maker if you get a wonky mould. I'm sure they'll exchange it for you.  No one has perfect QC.  I don't have a lot of moulds but the Tanner is my favorite. It casts true.

[WadePatton]

Check those balls in for roundness as well. They may not be perfectly round.

[Daryl]

Moulds are often casting balls of different diameter than stamped on the blocks. Some of that can be alloy as Wade notes, however oft times is just
a matter of fact even in pure lead.
I have a Lyman .570" mould that casts .574" x .574", perfectly round balls.
Taylor's .600 Lee mould, that supposedly had the blocks was pressed on a tungsten ball (their advertising) to ensure accuracy of size, yet it casts a .608" ball
in pure lead (X-ray wall sheeting).
I have had other moulds, one double cavity mould I sent to Hanshi for his new .40, that cast a .400"x .394 or 5" in one cavity and .400 x .400" in the other. I could
only use balls from the front cavity. The other one just about quadrupled group sizes at 50yards.
You pays your money and takes your chances, it seems.

[Don Steele]

If you have the weight, a few simple calculations will provide the diameter of the sphere.

[hanshi]

There are only a few molds that I've gotten around to measuring and the differences are noticeable.  I have a dbl cavity Lee .440" and an old Lyman .445" mold.  The Lee is is about spot on but the Lyman ball measures .442" in one plane to .444" at 90 degrees.  Both load, shoot and give the same accuracy in my rifles.  I tend to think precise ball dimensions aren't necessary for really good accuracy; say around 1" at 50 and maybe around a couple of inches at 100 yards.  For the died-in-the-wool accuracy crowd this simply wouldn't do.  But for the majority of us that level of accuracy is better than "just fine".  Face it.  BP muzzleloaders are much more forgiving than we are and very accommodating of loads.

[Daryl]

If you have the weight, a few simple calculations will provide the diameter of the sphere.

The size and shape of the sprue will add or subtract weight, as they are not perfect spheres, unfortunately.
My .495" Lyman mould, back in 1972 cast 185gr. balls in pb, plumbers lead - 98.6% pure.

[Maven]

Yes, you can use mathematics to determine the diameter of a sphere or you can use this and do a bit less calculating:  http://www.beartoothbullets.com/rescources/calculators/php/roundball.htm?v1=.495&v2=2876.1

Btw, the major manufacturers, e.g. Lyman, RCBS, et al., use different standards, i.e., alloys, for determine bullet diameter.  I wonder if that applies to RB moulds, which most commonly use "pure" lead?

[Daryl]

Plain Pb is called pure lead. What is pure to you?
Is it Plumber's Lead at 98.6% pure, or is it only 100%, which, as far as I know, isn't available anywhere.
I do know that the X-ray room wall lining of sheet lead is pretty soft. I have to add a small amount of tin
to keep it from over-drossing (oxidizing) while casting. If I don't ass about 1/2" of 50/50 solder to a 20 pound
pot of this lead, I cannot even cast 20 balls without fluxing and skimming off the oxidized dross. There is zero
different in al actuality of the hardness between no-solder and with it, the amount is so small, however it does
indeed assist in casting this super soft lead.

[recurve]

I did check "roundness" and both are uniform, the larger ball loads harder with my 10 oz denum .022 (groups seamed to suffer) tried pillow ticking .019 didn't seam to hold up, 50 yrds good ok/group 100 yrds no good .  I need to find 8oz denum .018-.019 or canvis. &/Or try some swiss 2f
The Load that grouped well with store round balls 60grns swiss 3f 10oz denum mutton lube
 Bobby Hoyt 1-56 barrel 42in .50 round bottum rifling
 
The green Mtn mold throws a very consistant ball on my reloading beam scale 173 grns,
the store bought varied 170-176, I had started grouping them by weight before trying to cast my own.
store rball

[Daryl]

Your crown is too sharp, recurve, for the tighter loads.
There is not rounding entering the grooves to allow movement of the lead in the patch.