We’ll need better definitions.
What can you tell us about the source table? Can you provide DDL and DML?
“Send to Report Builder” – do you mean populate another table for Report Builder to use as a source? Or perhaps use the output from the stored procedure?
For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden