[dwightlooi]

What is considered a good velocity spread for 45 ACP hand loads? In terms sd, es and mean, what can we expect?

 

[dwightlooi]

I am getting extreme spreads in the 30~40 range. But SD is bad at, well, close to 30. In other words, it's consistently all over the place!

Yes, I know mean has no spread; it's just the average. But it is useful to know what the mean is when digesting the SD or ES, because 22 SD and 56 ES at 900 fps one thing and quite another at 1150 fps. Transonic loads tend to be most sensitive to velcoity inconsistencies.

 

[dwightlooi]

To be honest, I didn't calculate the SD and ES. The Chrony did. It has a 32-shot memory so the sample size is usually 32.

I am not sure if they did it using "n" or "n-1" in the denominator. It depends on whether they consider the 32 shots the entire population which is one way to look at it, or that the 32 shots is a subset of a larger population which is also not unreasonable.

I guess I can find out by jotting down each measurement, doing it manually and comparing the results.

I load the 185 gr JSWC to 900 fps (5.0 grs of titegroup) which is not exactly transonic.

I also load the 185 gr JSWC or Nosler 185 JHP to 1150 fps w/ 8.5 of Longshot to simulate 185gr +P factory loads.