While a tight bushing on a standard barrel is a start at getting better accuracy out of a 1911, a loose fit of the slide to the frame and of the barrel to the slide will most certainly kill accuracy. A cheap addition to the barrel bush is the Wilson Combat Dwyer Group Gripper. Through a small spring in the recoil spring guide, and a notch in a special barrel link, the barrel is pushed up into the slide with enough force to make the barrel/slide return to exactly the same place with every shot. In my case it reduced my group sizes by about 30% (with the fitted barrel bush).
No amount of heavy barrel is going to make up for a loose slide to barrel fit and/or a loose slide to frame fit.
But this is just my experience (and that of Jerry Kuhnhausen):