Create a user-defined gap between two Bootstrap columns

Create a user-defined gap between two Bootstrap columns

I want to create little panels/dashboard for my interface. In my case I
want to have two panels like so
+-------------------------------+ +-------------------------------+
| | | |
| | | |
+-------------------------------+ +-------------------------------+
Generally it is easy with Bootstrap 3.
<div class="row">
<div class="col-md-5">
</div>
<div class="col-md-5 pull-right">
</div>
</div>
The problem is, the gap of col-md-2, as it is the case here, is way too
big. I cannot use a col-md-1 gap, because then both sides do not have an
equal size.
I also tried to add padding right and left, but that had not effect, too.
What can I do here?