Ok, now just how does this happen? (lead question)

[D. Taylor Sapergia]

Clark:  what kind of starter are you using?  May I suggest one that has a moose antler knob?  the added weight and density of the moose antler gets the ball into the bore, no matter it's bhn.  Once in the bore, it cannot be any tighter than any other ball, though, if if is elongated, there will be more bearing surface.
I recently (two days ago) re-sighted my Verner rifle.  It has a Getz bbl. with .50 cal bore and the lands are WIDER that the grooves...not optimal.  I loaded .016" denim patches with ease.  But they didn't shoot particularly well at 50 meters.  So I tried some .018" denim and had a $#*! of a time getting them into the muzzle.  Now, this is cotton that is compressed as hard as possible between my thumb and forefinger, with help from my other hand.  My philosophy is that that is how the ball/patch is received by the bore.  The heavier patches shot better, and I was able to come to a satisfactory result.
But a heavy dense starter knob, with enough surface area that a smack with the other hand is all that is needed to start the ball flush with the muzzle, is vital.

[JCKelly]

Your metallurgist is in hiding, as he has no practical experience with the hardness of nominally pure lead.

Jim K

[WadePatton]

Your metallurgist is in hiding, as he has no practical experience with the hardness of nominally pure lead.

Jim K

How does this happen Jim?  I thought our metallurgist understood all the structures of the alloys and manipulations thereof. Geez now we gotta study for plumbum certification... 

[Ugly Old Guy]

Could whatever you're using to coat the mold so the balls don't stick/solder themselves to the mold be raising the hardness of the finished balls?

Is there a chance there is a contaminate on your ladle?

Do all the blocks of lead measure the same hardness in several locations?
Maybe there is a slight contamination in the blocks?

Sorry, but I cannot think of anything else that might cause the problem.
I'm presuming you have not loaned that pot to anyone else, and no one is dropping a wheel weight or something in while you are not looking.

Is obtaining a new pot and ladle and comparing results an option"

I doubt the lead is removing any of the aluminum from the mold. The lead is not hot enough to do that?

[Dphariss]

No water quench. Just drop them from the mold onto my old towel and keep going. The balls are measuring true, at least caliper true. Maybe I should mic them to get a more accurate reading. The bore is .540 as best as I could tell without actually slugging the bore, but it does have odd number grooves so that would take some math work.

Maybe this particular barrel just likes loose loads. It's hitting where I aim and it easy to load, maybe I should just accept that for now and revisit this after I get a couple years of shooting through it.

If the balls measure the same as those previously cast of pure lead its not likely that the alloy is very hard if alloyed at all. But 99% pure could be anything being 1% what else. I am assuming the barrel has wide lands. These always load harder than narrow lands. You can order plug gages from MSCdirect.com that will let you check the bore with little measurements. If you think its .540" then get a .540 minus gage and see if it goes in the bore. If not then the  bore is under .540"
https://www.mscdirect.com/product/details/88854005
Or just shoot .530 RBs.

[Clark Badgett]

Could whatever you're using to coat the mold so the balls don't stick/solder themselves to the mold be raising the hardness of the finished balls?

Is there a chance there is a contaminate on your ladle?

Do all the blocks of lead measure the same hardness in several locations?
Maybe there is a slight contamination in the blocks?

Sorry, but I cannot think of anything else that might cause the problem.
I'm presuming you have not loaned that pot to anyone else, and no one is dropping a wheel weight or something in while you are not looking.

Is obtaining a new pot and ladle and comparing results an option"

I doubt the lead is removing any of the aluminum from the mold. The lead is not hot enough to do that?

I don't put anything on my molds, except a little soot from a match the first time they are used. No one uses my lead pots.

[Daryl]

I spray all of my moulds with moly bullet coating (Lyman or Ms. Moly).
This prevents lead sticking and does not change the dimensions - at all.