I have a 34 that is probably 15 years old. Maybe 1000 pellets fired. UTG Bugbuster 3-9 AO scope. Always accurate and dependable for pests until a few days ago. Suddenly missing starlings. On paper the shots group but the groups wander. This follows a strange cycle. At 50 feet from a rest I get 3-4 shots in a wide group at 6 o'clock two inches low. Next 2-4 at 6 o"clock 1 inch low slightly tighter group.. Next 2-3 shots 12 o'clock 1/2 inch high. Next 10-15-20 shots X one (large) hole. No adjustments made to the scope. I set the rifle down and replace a target or what ever and 9 times out of 10 the pattern repeats from scratch when I pick it back up. I went over every bolt and screw in the rifle and scope mount and all are tight. Doesn't matter what pellet I use of the several I have available. Bore is cleaned with pull through patches or felt pellets about every 100 shots. That doesn't seem to alter the cycle. This cycle has repeated more or less the same perhaps 10-12 times.
I am more of a firearms user. Been shooting them 50 years. Never saw or heard of this type of thing before. Tomorrow I'm pulling the scope and trying iron sights. Thoughts?

I am more of a firearms user. Been shooting them 50 years. Never saw or heard of this type of thing before. Tomorrow I'm pulling the scope and trying iron sights. Thoughts?
