Had the same issue on my dads 10xs raider, the barrel ports had become miss aligned after the barrel became loose, this meant that not only did the barrel wobble and throw the zero off the power levels were all over the place
After a service at A&M Custom Gunsmiths it is now shooting pellet on pellet.
Make sure everything is tight including any barrel bands etc cos if its loose the barrel will wobble all over the place
You will be able to tell if the barrel is loose you can rotate it by hand
ATB
Adam