The way the Sheriff explained it to me, some states (this one doesn't) have laws that require that an SBR be registered with the ATF. Since that isn't the law here, local state-certified law enforcement would be essentially looking to enforce federal law if they asked. Here, they don't ask. In some states, they might.
OTOH, it's no big deal to keep a size-reduced scanned copy in a battery storage compartment and doing so might defuse a misunderstanding some day. So I do.

