Originally Posted by 7stw
ThE reason I asked about how many shots and how close, is that barrel heat will play a part of your SD, and ES. As the barrel heats, it flexes more, and sometimes gets tighter and will effect speed/ pressure.
I'm not sure if I agree with your causality.
Chamber temperature heats the cartridge and cartridge temperature does most certainly affect MV. If you ever let a cartridge sit for long in a hot chamber, that shot will likely print high.
As to the OP... Your sample size is way too small. You need to shoot/record a lot more samples to be statistically significant. If you're happy with group sizes, then keep shooting. If you question the consitency of your chrony, then shoot longer ranges. Groups don't lie.