were not sure you wanted to know the answer?

Yesterday I cast bullets for my 32-40 using 24:1 lead at 725 degrees and a Saeco mold that I bottom poured.  After culling the obviously flawed and underweight bullets, I had 128 bullets that resulted in the following:

93 bullets that weighed 205.16 grains +/- .2 grains
12 bullets that weighed .2 to .28 grains above the 93
15 bullets that weighed .3 to .38 grains above the 93
7 bullets that weighed .4 to .48 grains above the 93
1 bullet that weighed .54 grains above the 93

Why do the 35 bullets shown above weigh up to .5 grains more that above the vast majority of the other bullets?  I can see no obvious differences in all 128 bullets.

Am I setting a weight variance standard too low or ?????????????? is causing the heavy bullets?

Another reason I prefer to ladle is the melt will stratify (different temps at different depths). With a ladle when I return it to the melt between bullets I always give the pot a stir to break up any stratification and insure there is an even temp in the melt. YMMV.
Am also a PID junky.

I have always believed that the best Temperature is at the top of the pot. Thermal circulation, Heat rises. This also improves the mixing of the Alloy. Casting is best done as a Steady State 
process. If you spend a lot of time looking at the bullets you just cast, rolling them around on the towel. You will be causing 
Temperature changes in both the Melt and the Mold. Once I get the Alloy and the Mold up to Temperature and casting good 
I just go for it. Get a good rhythm going keep it going. I usually have an Ingot on the side of the Pot getting heated up
so it does not cause a significant Heat loss when I add it to the Pot. I like to get Temperatures high and when I have every thing going I get a little impatient waiting for the sprue to freeze off. I also like Frosted bullets. When you see that you are getting little short pieces of Vent lines showing on the Bullet there is no doubt that you are reproducing the Cavity just about as well as can be done. I first started Casting when I was 15 years old, am now 75, thats 60 years of casting experience. HTH Regards, FITZ.

I think the more important question is how much effect a half a grain weight difference in a 205 grain bullet will make on the target.  Sometimes I think we get too wrapped up in minor details and ignore the big picture.

JS

Let's get to the real world:
Load 5 of the lightest, 5 in the middle, 5 of the heaviest, and a mixed set.
Carefully shoot a group with each (at 100 yards or whatever) WITHOUT YOU knowing which group you are shooting.
If you get the same results as about 99% of folks, there will be NO difference, within the error of your ability to shoot sequential groups.
I have NEVER seen any difference, out to 200 yards, of cast bullets having a weight range of +/- 3 gn.
In fact, as long as my bullets have completely filled out bases, even wrinkled bullets do just as well out to 200 yards.
Beyond that, perfection becomes more important, but not nearly as much as so many believe.
We can "hand wave" all sorts of theories, but if it doesn't have any real world effect, who cares?
Personally, I think you are doing GREAT and should be quite happy.