Hotkey access to a browser URL based on a URL part on the clipboard
Since you are already using Quicksilver, this should be pretty easy:


Install the web search plugin
Add a custom web search list to your catalog 
Add the URL to that
list, in the form http://example.com/defects/*** (that is
with 3 * instead of your "nnnn") 
Add a trigger for "Clipboard
Contents" -> "Find with..." -> "your new websearch URL" and assign
your preferred hotkey.
When you use the trigger, it opens the request page in a new tab of your default browser (with the stars replaced by the text on the clipboard.


That way you can use your custom URL just like any other web search with Quicksilver.