Hi Jim before buying a new pistol or adding wieght to your muzzle try this, get your self 12" of fishing line and a tub of lead fishing wieghts, loop and tie off the line and add wieghts to the line and loop over the muzzle so it pulls the end down, keep adding wieght until it shoots the way you want. it's a cheap option to find out the wieght required, once you know the wieght you can add it permanatley inside the muzzle.
buying a heavier pistol doesn't mean you will hold it steady, and can even have the reverse affect IMHO
Jason