I have the same gun and it took me a little while to get my gun to shoot good also but after about 30-40 shots thru it, it shoots great now. I use 2 triple 7 pellets and a 245 grain powerbelt aero tip bullet. I shot 2 deer with it this past season and am very impressed with the gun. I did not get a complete pass thru on the deer but they both went down within 50-60 yards of where they were hit.
Good luck hope this helps.