Problem
Courts have ruled a few times requiring "Knock and Announcement" on search warrants that officers must announce their intentions before doing certain things - such as forcing open the door or releasing a police canine. There is some discussion over "10 seconds" being an appropriate time.
Place yourself in the shoes of the person serving a search warrant for narcotics. You don't have specific information that there's a firearm in the house - and you don't have specific information that there isn't.
Where is the balance between allowing people a reasonable time to open the door willingly or giving themselves up before breaking down the door to prevent dangerous people from destroying drugs or picking up a gun?