You should see an increase of one magnitude or another, but it should be a very small difference, perhaps not noticeable. If the ammunition was loaded at the same altitude, then the only factor is the resistance of air in the barrel, and the resistence of air from the barrel to the chrono. I can't see it as being significant. Out at 100yds it would probably have a considerable impact, especially in the rifle sports.
H.
Maybe the temperature differnce (70 versus 102) made up for the alltitude difference resulting in the same chrono results?
This was a pistol only match and I know rifle would be a whole other can of worms.
It was just my perception that with my 38 Super Comp loads that altitude didn't make any difference.
FM