I was having the same problem with my 30-06 and 223 Encore barrels. It came down to clean versus dirty barrel. If I cleaned the barrel, the first shot was about 12" high at 100 yds. Each shot is a few inches lower, until they reached 0" high. Windage was unaffected. Now, once sighted in, I leave the barrel dirty until the season is over. You might want to try running a clean dry patch through though. This is a known issue at TC.