I have an SBR (should be the same in the eyes of BATFE) and my dealer said a copy of the paperwork was acceptable. Not only that, but he suggested NEVER carrying the originals - subject to loss or damage.
Having said that, an SBR cannot be transported across a state line without written permission from BATFE - not really sure if this applies to SBS or not, but I would think it does. There is a "Transport" form you fill out and send in (address on the back of the form) it normally comes back within two weeks.
I transport to shoots in Florida and Tennessee. I send in a form for each state, each year with a one year duration on them. This keeps me clean for a year to shoot in either state. I carry copies of these also, not originals.
Hope this helped.
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