i have a marlin lever action that is by no means a percision rifle, but thought this forum would yield answers. yesterday I had a decent cold bore 3 shot group inside 2" at 80yds at POA with iron sights. went back today to double check, my sights were set the same, same distance, and the first shot hit 9" lower than POA. The second shot hit 2" lower than the first. If that was my deer he'd be a runnin! I then moved my elevation rail up one notch and shot a 3 shot group of 3" at POA. Im sure the elevation rail did not move overnight because i marked it's position. I did not clean it last night knowing i was going out again today. What could cause that kind of drop from yesterdays aimpoint? i only put 5 rounds through it total yesterday. im baffled! it shoots o.k. groups which from one day to the next hop around like it was wearing a chinese scope...