I think I need to tighten up my procedures when I chronograph my loads. When I’m checking loads for my AR-15, it’s pretty common for my velocities to increase throughout the string. The first shot is frequently the slowest. I’m guessing that the increasing barrel temperature is the reason.
It seems to me that if I’m testing hunting loads for a bolt action rifle, for example, I should let the barrel and chamber cool off and try to measure all of my velocities from a cold bore. However, if I’m testing varmint loads from my AR-15, I might want to measure velocities with a warm barrel.
What are your thoughts?