More on Red's Trading Post
Story here. Back when they had paper records (as do most FFLs, since a computer program has to have ATF approval and few do), they were told to file 4473s for past years in alphabetical folders (i.e., 2006 -- all last names beginning with A) but have them in chron order inside the folder. That'd make a trace report a bit simpler, since bound books would give you the date of sale. Then a new ATF inspector came around and wrote them up on a violation notice for that, pointing out that the regs say you can put them in alphabetical order (sorting out all sales for an entire year) or chron order, but the regs say nothing about a mixture of the two systems.
Red's has since managed to lease an ATF-approved computer program and used that. Now the inspector has decided the system is inadequate because of how it handles lay-away sales.
The story illustrates how complex and often arbitrary the system governing licensed firearms dealers is. If you have an inspector who is decent and practical, life is simple. The same system overseen by an inspector who is a nit-picker, or has a grudge for you, can be impossible.