Chris, a check with the FAA website actually shows that N300R is a reserved registration since 19/07/2010and it is not allocated at this time
The Beechjet you refer to has been re-registered N330R and the B350 became N270AB.
If you see it, it must be one of the previous users still showing its old hex, probably the Beechjet as it was re-registered in June this year
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Alan