We've seen a lot of custom 10/22's of the years and almost all of them went from an 18" barrel to 16" or less yet only one person commented that they contacted the CFC so I wouldn't say there is a lot of worry about this issue. The owners of those rifles know that they are legal. If the CFC can't or won't issue a proper registration certificate however, it might be worthwhile to bring to the attention of the CSSA, Stockwell Day, and Garry Breitkreuz.