I have noticed a trend in one of my barrels. The bbl is a .280 remington prohunter. This has perplexed me for quite some time. I have never experienced this phenomenon to this degree. The first shot out of either a clean cold or fouled cold barrel is a consistent 1.5 higher than the group. If I let the barrel cool for 15 minutes after the first shot to ambient temps., I can group with the 1.5" high shot all printing less than 1MOA. After the first shot, if I shoot a string, it will shoot a little less than 1 MOA 1.5 lower than the first cold shot. I have noticed it does not matter whether the barrel is clean or fouled. The results are the same with both. It is not a terrible issue as I have the cold shot zeroed 1" high at 100 and I hope not to take too many follow up shots. I do find it interesting, and was wondering if any of you have experience and maybe a solution for this. That particular load is a 140 grain sierra game king over 56.5 gr of reloader 22 seated 7 thousandths off the lands. It is probably important to note that It does the same with all loads I have tried even including factory ammo. Cold barrel=1.5 higher than group. What is up with this?