What would be considered a reasonable Extreme Spread for hand gun loads running 700 fps to 1000 fps?
As an avid shooter and reloader, I am familiar with many rifle loads and what to expect when chronographed.
More recently I have been running some of my light and mid-range 357 Magnum loads over the chronograph and the extreme spread, "ES" of many of these loads seem quite high. Some powder puff loads have an ES of 14 & 15 % and one at 18% of the average velocity. These loads run average velocities of 750 fps to 800 fps.
A load using a 145 gr. cast wad cutter over 4.0 gr. of 231 gives me an average velocity of 782 fps and ES of only 24 fps, only 3% of the AV. Another load, a 150 gr. cast round nose boolit over 4.0 gr. of 231 ran an average velocity of 747.5 fps and the ES was 44.8 fps for 6%.
I figure the higher the ES is, the less ballistic uniformity I have and that usually means less accuracy.
I have other 357 mag. loads to run over the chronograph that are known to be accurate and some that are what I call inconsistent. The inconsistent ones will sometimes shoot very tight groups and other groups are not much to talk about. This happens when five consecutive ten shot groups are fired.
It will be interesting to see what the chronograph will tell me about these loads.
I have several other hand gun calibers I intend to chronograph. They run from 38 Special to 9mm,38 Super, 45 ACP and 45 Colt. Would the acceptable ES be pretty much the same percentage for all calibers?