Gents,
I've begun to question the wisdom of weight-sorting bullets into “batches” in the hope of shooting tighter groups with weight-matched slugs.
Except in the case of gang molds with significant weight variation among bullets cast in the various cavities, it's my belief that any bullet that weighs appreciably less than the “standard weight” for the mold is a flawed bullet that can't be depended upon to shoot as well as the heavier standard weights pills.
In other words, a bullet weighing 198.1 grains from a cavity that normally drops 201-grain slugs is a less-accurate bullet with an air pocket in it.
As long as normal casting precautions (maintaining alloy consistency, melt temp, mold temp, mold-handling and maintenance procedures, etc.) are taken, it seems to me there is no other explanation for an underweight casting. Such bullets must have a void-pocket in them, and, depending on where the void is located, accuracy will suffer accordingly.
So, sorting bullets from a “201-grain mold” into weight ranges lower than the standard is merely classifying the degree of inaccuracy that can be expected from each weight range.
Considering that “201-grain mold,” I'd expect a batch of bullets weighing within .2 grains of each other -- in a range of 197.2 to 197.4 grains -- to group poorer than a batch of slugs varying a full grain in weight, but in a range of 200 to 201 grains.
A batch of the same bullets varying in weight not at all -- each weighing exactly 196.8 grains -- will likely produce even poorer groups than the heavier batch that varied .2-grain.
So, weighing to precisely match bullets weights within a “batch” in the search for greater cast bullet accuracy is, I think, a waste of time.
Any bullet that weighs less than standard is, it seems, by definition, an inaccurate bullet. The degree of inaccuracy will be determined by the degree of weight loss, and the positioning within the bullet of the air pockets responsible for the lesser weight.
So, if I was seeking ultimate cast-bullet accuracy, I'd toss back into the pot any bullet the weighed less than 201 grains. Or maybe, in a concession to reality, I'd toss back any bullet weighing less than, say, 199.5 grains.
Now, if only I can learn to shoot well enough to the see the difference on paper between a batch of 201-grainers and a batch weighing 196 grains, I'll be a contented marksman.
Anyway that's my opinion, and why I don't bother to weight-segregate other than to toss back any really light bullets.
Happy trails,
-- Cary Gunn --