Well, a bit more information from the importer. ATF doesn't give a reason when an import is rejected, nor do they publish a list of models which won't pass the drop test (apparently for fear of manipulation). The earlier comment that the gun was 'too small' was from an employee of the importer. If a revolver meets the 45 point factoring test and is still rejected, it is inferred that it fails the safety test, which is clearly the case with the SAA. So, knowledge gained and no real harm done as I will consign it back to the auction house.