I have a 12 ga pump with a smooth bore. I sighted it at about 40 yards before the season and it shot pretty much right on the money. I then took it apart and cleaned it. The second day of the season i shot at a doe about 50-60 yds away and missed. The best i can figure i shot under it (looking at the bullet strike on the ground and position i was in the stand). I resighted it and it shot about 5-6in low at 40 yds. I determined that taking it apart somehow caused it to shoot low. Well I haven't shot it anymore until this weekend and at 60 yds it shot 7-8in high. What is going on with this thing? All the shot groups were pretty close together so I know it wasn't my fault. Anybody have any ideas?