Gun Blueprints have always been a little too complicated in COD, it's easier to think of them just as a version of a weapon that comes with atachments included - often for a weapon that you haven't already unlocked.
Available through the Battle-Pass, the COD Store, completing challenges and leveling up, Blue-Prints are a fun way to try out different weapons that you otherwise pass on because you haven't unlocked those all important attachments.
Thanks, Rob.
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