shilo,
Don't shoot conicals with pellets. If I remember correctly it says something about that on the box or information that comes with the pellets. You can shoot PowerBelt conicals with pellets because they have the plastic skirt on the base.
Get yourself some 777 loose powder in the 70 to 80 grain range for starters, then work up in 5 grain increments until accuracy starts to suffer, then go back to the most accurate charge. The wads will generally help tighten groups because they seal off the base of the conical to help prevent gas cutting of the base and keeps things more consistant from shot to shot.
If I remember correctly you shoot an Omega, the QLA barrels for some reason generally do not shoot conicals worth a hoot. So, even if you are doing everything right, the gun just might not be capable of shooting conicals well.