I have a 16 year old Gamo CFX air rifle that I use for offhand practice, I have not been doing this for about 6 weeks and the results show that. I rarely shoot this rifle at paper but this morning, disappointed by my offhand efforts, decided to check the scope and rifle on a target at 20m, shooting off sticks. The fault does not lie with the equipment.
I normally shoot with the scope, a 25 year old Tasco 3-9x40, at 3x but decided to set it at 9x for this. The 5 shots at the top target was fired with the scope at 9x and show vertical stringing. I then set the scope at 3x and shot the target at the bottom left, much better. Being a scope intended for center fire rifles, parralax is probably set at 100m. Is the stringing the effect of parallax?
https://i.imgur.com/qejAM1m.jpg