I thought I had read (in the context of FN Scars), that although engraving on the short barrel was proper, you couldn't then change back and forth to the longer barrel, because when the longer barrel is on, you have a registered SBR (although not currently in that configuration), that doesn't have engraving on it. Maybe it's different for SBRs than SBSs. Maybe the other info I read was just wrong. Maybe I misunderstood the prior threads. Any follow up education would be helpful. Thanks.