Hello chn_cntbtt,

Thank you for posting in the community.

I know it`s been a while since you posteb but if you are still in need of assistance I would be glad to help.

What I can suggest for achieving your requirement is using the FillSceneGraph server side event of UltraChart. In this event the width of the bars could be set as such:

  protected void UltraChart1_FillSceneGraph(object sender, Infragistics.UltraChart.Shared.Events.FillSceneGraphEventArgs e)
     {
                 foreach (Primitive p in e.SceneGraph)
             {
         Box box = p as Box;
         if (box != null && box.Layer != null)
         {
             //set the width of the bars
             box.rect.Width = 50;
                    }
                   }
    }

I also made a small sample illustrating my suggestion and I am attaching it for your reference.

Please let me know if you have any additional quetsions regardng this matter.