At 7 yards (21feet), the shoots should all be in the red and 9 ring, and maybe an occassional 8. What stance are you using? Weaver? Isosceles? I shoot Isoceles now. Was shooting low 80% using the Weaver, but since switching to the Isoceles 4 years ago, I'm shooting 99-100% on qualification now. Looks to me you are trying to anticipate the shot going off (jerking) and not focusing on your front sights. Line up the sights, center mass. Once you do that, focus on the front sights. The front sights should be crystal clear, and the background (target) should be hazy/fuzzy. If the background (target) is clear, you are not using the sights and are trying to see where your shots are going onto the target just before pulling the trigger. Only use the tip of your trigger finger. When you pull back on the trigger, it should be one fluid motion, and each shot should be a surprise. If you anticipate the shot going off, you will throw your shots off. For longer range shots, breathing is important too. I exhale as I squeeze the trigger on 15yards +. This has helped me out tremendously. There are plenty of material on the Internet to help you out too. Having a proficient shooter at your side is alot better though.
I just shot my first Sig 220 today. Wow! Are all 220s tack drivers?? I think it shoots better than my Para-Ordnance Tac Four. At 25 yards, I'm making head shots on a man-sized target, and I was shooting Wolf ammo too. Just have a proficient shooter give you pointers and look up some reference material and apply it on the range. Enjoy your Sig 220, I know I will. This is one gun I plan on keeping.