Hi we run std 2008 r2.   On my col heading text boxes and data text boxes i'm purposely picking only borders above and left in an attempt to get rid of what looks like a double border between text boxes. 

The only places I see what appears to be a single thickness is the left of the 1st column hdg and data, and above any col hdg text box I set this way. 

Also, when I pick .5 instead of 1 pt thickness, ssrs always puts it back to 1 pt.

How can I get the appearance of single thickness borders instead double?

Hi, 

According to your description, you want to change the width of table borders, right? 

In our local environment, we have tested this scenario and reproduced this issue that when setting the width to 0.5pt on Border tab, Reporting Services always reset the width back to 1pt. Based on my research, we can set the border properties on Properties window. In your scenario, we would recommend to submit this issue to the Microsoft Connect at this link https://connect.microsoft.com/SQLServer/Feedback.

For your requirement, if you want to set the border width, you can click the text box and press F4. Then set the border width, color and style on Properties window. 

If you have any other question, please feel free to ask. 

Regards, 
Shrek Li