RocketFFL summarizes the bill:
…Currently, a Federal Firearm Licensee (FFL) must satisfy background check requirements prior to transferring a firearm to a non-FFL. In most cases, this involves running a background check on the individual purchasing the firearm.
Usually, a response to the background check is received by the FFL within a few minutes. However, sometimes there is a delay of the response for myriad reasons: slow system response, anomaly in the person’s background, or multiple people with the same name.
Thankfully, as to not violate the Constitutional rights of law abiding Americans, if a denial is not received within 3 days, the FFL may transfer the firearm to the customer. This prevents the government effectively banning guns by delaying a background check response.
Anti-gunners refer to this check on the government’s power as a “loophole” and they are trying to end it…