I have noticed that as the barrel of my rifle heats up, the readings from my chronograph also increase. Has anyone also noticed this trend? As part of my testing I fired 10 shots in quick succession over my chronograph starting with a cold barrel. The rifle was a .338 Sako with a standard weight 24” barrel. The first four shots all showed an increase in velocity over the preceding shot, then once the barrel was quite hot the velocity readings for the remaining shots all hovered near each other. This resulted in an extreme spread of about 50 fps. The next test I fired 10 shots and waited for the barrel to totally cool between each shot. The E.S for this string of shots was in the low teens. I am wondering if this is due to the light weight barrel and if the same thing happens with a heavy barrel?