Raymond- is correct. That SBR MUST be marked with the makers name, city, and state in a "conspicuous location" which means it must be visible to an inspector without removing parts to see it (it can be marked on top of the receiver though and under a scope mount but not under a grip or forend. The reason is the rifle does not have a scope or base on it as sold new, so marking anywhere it can been seen on a stock rifle is OK, I also have an e-mail on that). That is a fact and anyone who does not believe it and follow the rules can be looking at a serious fine, confiscation, and even jail time.
Right at the top of this very forum is a post about what the ATFE has said about the topic. I have letters (not just e-mails) from the ATFE also regarding this topic and they are adamant about it, the maker of the SBR MUST mark it with name (no abbreviations other than middle initial), city, and state.
If you do not have it done, you had better get it done. If for some reason the ATFE inspected your SBR and it is not marked, and you have an inspector that is up on the law (sad to say but many are not) then you could be in for some serious legal problems and the loss of your firearm.
