Typically I like developing reports with a procedure (kept within the database) and an RDL file (which executes the procedure). To make these as easy for deployment as possible to the greater audience, I embedded the query directly into the RDL file. The most simple way to view them would be to do the following:
1) Open the RDL (not in visual studio, but in the XML view. If you are not sure how to do that, just put the file somewhere, like your desktop, and double click it).
2) Search for the text string "<Query>" (do not include the double quotes - only what is inside the quotation marks).
3) You should be taken to the section in the RDL file that contains the query (some of these report have multiple queries). Just past the <DataSourceName> and <CommandText> tags begins the SQL code. That should be what you are looking for...