I had the same problem with my bsa tactical it just didnt seem to want to zero at all. I tried every pellet on the maret,every position and 3 sets of mounts and 2 scopes the gun just would not zero!! I also checked the silencer...This is something you should do if you havent already...check the silencer on your gun is not in the line of fire meaning it is clipping the pettets on there way out making the pellets fly everywhere... just a thought
Steve