Measure twice cut once. Well in the case of selling firearms you should probably measure a few more times and understand ATF NFA guidelines of what constitutes an SBR. Josh P. saw this at a local Cabela’s. The store purchased a used Remington 700 chambered in .300blk and it has a 15″ barrel. Josh brought this to their attention and they are looking into it.  If they had sold it obviously the customer would be in possession of an unregistered SBR. But what ramifications would the FFL receive?