Repeat the test 3 times to see if the same thing happens, might just be operator error
High shot on a cold/clean bore is unusual in my experience, mine tend to go slightly low. Couple of dry patches before shooting generally reduces the difference between clean and fouled barrel.
I'm assuming you are shooting at the same distance that you zeroed the scope ?
There are also different states of "clean"... Carbon ring in the throat area can cause vertical, short stroke the first 6-8 inches of the barrel with JB paste. Also leave a solvent like hoppes soaking in the barrel overnight and see what comes out on the patch after a day or 2.
Bookmarks