I remember havin the same problem. I have a Knight Disc and that's about as good as my groups get at 150, but before when I was struggling with my patterns, I was a matter of FEET off. Someone told me to make sure that I'm swabbing in between shots; that cleared my inaccuracy right up! I also found that I was using too much power. 100 grains of Triple7 pellets is JUST right in my gun.

PS - If you're worried about your shots being a little inconsistant because your scared of missing a deer, and your margin of error is only a matter of 3 inches, you have to figure that the kill zone on a deer is nearly triple your error.

Hope this helps!!