Why are chronographs important for load development?
Especially when several people shooting the same stuff will often have over 50 fps spread in average velocity and standard deviation. Who's numbers best represent the loads real data?
I have found a few good uses:
1. Knowing muzzle velocity allows me, through more physics calculations, to figure kinetic energy (use of KE on terminal performance is disputed) as the bullet velocity decreases with distance, ultimately finding a point where the round may no longer be considered "effective" on game.
2. It save me $, even if just a little. For example, if the gain in muzzle velocity variance from 43.0-44.0 gr or H4350 is negligible, then I will go with the lesser of the two simply to squeeze a few more rounds out of a pound of powder as well as to keep pressures down to the lesser if the gain is not worth it.
3. My chronograph has shown me round consistencies that I would not have otherwise known. For example, when loading .357 Magnum rounds for my carbine, through many rounds of testing, I have found that my velocities are not only more consistent with one powder over another, but also that gap tightens even further when different primers are combined. All of this would have been unknown without a chronograph.
4. Using a chronograph has sped up round development while reducing cost in both time and money, ensuring efficiency with every free minute and dollar that I have.
*Note: I also have seen that my velocities are seldom as high as a loading manual advertises due to both shooting conditions (their testing is done indoors in a controlled environment) and the rifle/handgun used, as their are often custom/long-barreled test weapons. I do not use software, just a plain old pen and paper to record data.
Hope this helps.
-SmokingFrye
