How to Set a gridview column width when binding to a datatable

I am binding a table to a gridview in asp.net as such

grdIssues.DataSource = mdtIssues;

grdIssues.DataBind();

The problem is I cannot then control the column width, asp.net seems to decided on it's own what width each column should be. Methods such as

 grdIssues.Columns[0].ItemStyle.Width = 100;
 grdIssues.Columns[1].ItemStyle.Width = 100;

don't work because the columns are created dynamically. I cannot believe there isn't a way to do this short of manually creating each column and filling each row.