I knew of a shop that had its' permits pulled about 25 years ago. The owner said he could not imagine why, but the fact that this fellow had a reputation of being the go-to guy for off the books repairs might have had something to do with it. Need a revolver barrel replaced? He seemed to always have a few used one sitting around. If you had $25 he had the repairs done while you waited. Cash only on such sales also drew a bit of attention from the Cops that shopped there.

All permits holders have to 'secure' the guns they have for sale. This is a pretty broad term and it would be easy to run afoul of it. I mean, how secure is 'secure'? A normal gun safe, a room sized safe, an empty cigar box?

The bottom line is that if the ATF wants you shutdown they don't have to look very far to find a violation if they look real hard.