I had to fix a report the other day that printed gray table borders out on hardcopy, but, the screen preview seemed fine.
After editing your report in Visual Studio the report preview seems fine on the screen, as designed. Publishing the report to SSRS and previewing the report from the server the report still seems ok on the screen. However, when it is printed gray lines appear on some of the table borders.
Open up the current version of the rdl file for the report and edit the xml. Remove all xml child elements within TextBox or TableCell elements that have a element other than and make sure that the element value is set to Black. Gray lines should disappear.
Open up the current version of the rdl file for the report and edit the xml. Remove all xml child elements within TextBox or TableCell elements that have a