The National Rifle Association is teaming up with the Mountain State Legal Fund to challenge a New Mexico law that puts a seven-day waiting period on firearms purchases. On Wednesday, the NRA announced on its website, “New Mexico’s ‘Unlawful Sale of a Firearm Before Required Waiting Period Ends Act’ requires the purchaser of a firearm to wait seven calendar days before taking possession of the firearm — even if the purchaser immediately passes a background check. While it provides an exception for concealed carry permit holders, it provides no exception for urgent circumstances, such as when a…