In an attempt to remove all variables possible from my first load development task, I decided to weigh my bullets to come up with 20 that weighed the same.
I went through the whole box (Horndady 143gr ELD-X, 6.5CM)
I bagged 'em all on a 1/10 grain variable.
My largest sample was 27 bullets at 143.2gr.
The next highest count was 12 at 143.1gr. I had 10 at 143.3 & also 10 at 143.4.
The spread was from 142.4 to 143.5.
The mean was 143.026. The Median was 143.15. Std Dev was .3196.
If I had just loaded without checking bullet weitghts, is this enough difference in bullet weights to cause “flyers” within my groups? The span is 1.1 grains on a 143.0 gr bullet, which is 0.7% of the “advertised” bullet weight.
What percentage of bullet weight is significant enough to create differences in point of impact?
Cool information to read through. I’m glad you posted that.
I checked, and the 1.1 grains of spread in bullet weight would account for less than one one-hundredth of a mil at 1000 yards with most cartridges.
It’s always possible that the anomaly in weight may also be a weird shape and affect the BC in other ways, but after running the numbers here, it doesn’t seem to be worth worrying about that little of a variation.
Thanks, JIm. I wondered, too, about shape & placement of the “odd” mass… would it affect CG enough to change spin & stability?
There is an interesting example on pg 27 of the Hornady manual (11th edition) where they talk about a press developing “a few thousandths of an inch play in its cup feeding mechanism” and it threw test groups from .205" to .820".