Since Breitbart News first broke the story of Mark Kelly's purchase of an AR-15 rifle, numerous readers have emailed to ask: "Why is Mark Kelly's AR-15 still at the gun store?"

The state of Arizona does not have a waiting period for purchasing firearms. Rather, customers take the guns home with them as soon as they pass a background check.

In this case, however, the wait is due to the Tucson retailer's own self-policing.

According to sources, another customer either traded in or sold to Diamondback Police Supply the AR-15 Kelly later purchased. When that happens, the store puts a 20-day hold on the firearm to be sure it does not come up as stolen in a police report or show up linked to a crime in a database.

Once this 20-day hold period is over, Kelly will able to pick up his gun. 

This is why Breitbart News reported that Kelly had yet to pick up his AR-15 on March 9 and why Kelly told Wolf Blizter he still didn't have "access" to it on March 11.