As a Type 3 FFL (C&R) holder, we are subject to an annual inspection of our C&R guns and bound book from the BATFE. I have yet to be called for inspection, but from what I have read, the common practice is to have all your C&R guns out of your safe and ready for inspection before the agent enters your home.
What if the agent asks to view the rest of your collection? What if the agent suspects you may be hiding certain C&R weapons from your bound book and demands to see them all to make sure?
These reasons could be used as the guise to also try to spot any banned "assault rifles" at the same time. This worries me greatly.