Thread: cold/clean bore shot

Went to the range to check this, was horrified to find that my first shot was 10inches above the aimpoint but perfectly inline. I then fired a three roud group and they were all 2.5 high above the bull and just over an inch. I have found the rifle shoots better fouled so when I clean the barrel all I do is remove is the powder residue not the copper. I also store my rifles with a layer of oil on the bore which is then removed prior to firing. Obviously after running dry patches through there will still be small traces of oil remaining. Would this cause the first shot to be so far off?